Mathematics 9 - Variation & Equations

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Questions and Answers

What is the mass of an object if the force remains the same at 225 N and the acceleration is doubled to 10 m/s²?

  • 45 kg
  • 2.25 kg
  • 0.5 kg
  • 22.5 kg (correct)

Which statement correctly describes the simplification of the expression $\left( \left( \frac{4x^{-3}y^{-4}}{7x^{-5}y^{0}} \right)^{0} \right)^{-1}$?

  • The result of the expression is 0.
  • The entire expression equals 1. (correct)
  • The expression cannot be simplified.
  • The expression simplifies to the reciprocal of its base.

How should you calculate the distance from Yor's house to Anya's school given the description of their locations?

  • Measure the distance on a map.
  • Utilize the distance formula directly.
  • Create a right triangle and calculate using sine and cosine.
  • Use the Pythagorean theorem to find the distance. (correct)

What is the distance from Yor's house to Anya's school given that Yor walked 14 km south and then 8 km west?

<p>16 km (D)</p> Signup and view all the answers

Which student's statement about zero and negative exponents is true?

<p>A number raised to zero is one. (B)</p> Signup and view all the answers

What should be the outcome of simplifying $\left( 64x^{8} \right)^{\frac{1}{6}}$?

<p>$8x^{\frac{4}{3}}$ (D)</p> Signup and view all the answers

What does negative exponent notation signify when applied to a base number?

<p>The base is turned into its reciprocal. (A)</p> Signup and view all the answers

What is the correct interpretation of the term 'the power of a power' in exponent rules?

<p>You multiply the exponents. (D)</p> Signup and view all the answers

What is the simplified form of the expression $\frac{a^{\frac{3}{2}}*a^{\frac{5}{4}}}{a^{\frac{1}{4}}}$?

<p>$a^{\frac{7}{4}}$ (C)</p> Signup and view all the answers

What is the result of simplifying $\left( \frac{16x^{12}}{81y^{4}} \right)^{\frac{3}{4}}$?

<p>$\frac{8x^{9}}{27y^{3}}$ (B)</p> Signup and view all the answers

What is the final answer Keith should arrive at when simplifying $\frac{3m^{-4}n^{2}}{15m^{-3}n^{-2}}$?

<p>$\frac{1}{5m n^{4}}$ (D)</p> Signup and view all the answers

What is the MOST efficient method for simplifying $\frac{\sqrt{75x^{4}}}{\sqrt{3x}}$?

<p>The expression should be placed under one root first and then simplified. (A)</p> Signup and view all the answers

Is the expression $\sqrt{\frac{8}{7}}$ simplified already?

<p>Yes, because the fraction is in its simplest form. (D)</p> Signup and view all the answers

What is the simplified expression of $\sqrt[4]{128a^{12}b^{17}}$?

<p>$2a^{3}b^{4}\sqrt[4]{2b}$ (B)</p> Signup and view all the answers

Which approach is more efficient when simplifying $\sqrt[4]{81x^{12}y^{8}}$?

<p>Jimin's approach is better because it reduces steps by grouping terms. (A)</p> Signup and view all the answers

What type of variation is occurring when one variable increases while the other decreases?

<p>Inverse Variation (D)</p> Signup and view all the answers

How does the cost of a product M relate to the price of production N if M varies directly as N?

<p>M increases as N increases. (D)</p> Signup and view all the answers

What type of variation is demonstrated by the relationship of profit with the number of items sold and the selling price per item?

<p>Combined Variation (C)</p> Signup and view all the answers

Which student correctly translated the formula y = \frac{kx}{z} into words?

<p>Joseph: 'y is directly proportional to x and inversely proportional to z.' (D)</p> Signup and view all the answers

Based on the table values provided, how does N relate to M? M 5 4 3 2 1 N 25 20 15 10 5

<p>N varies inversely as M with a constant of variation of 5. (C)</p> Signup and view all the answers

If a force of 150 N moves a 10 kg object with an acceleration of 3 m/s², what force would be needed to move a different object at the same acceleration?

<p>225 N (B)</p> Signup and view all the answers

What happens to the acceleration of an object if the applied force is doubled while keeping the mass constant?

<p>The acceleration is doubled. (D)</p> Signup and view all the answers

What type of variation is represented when a variable is directly affected by two other variables, one directly and the other inversely?

<p>Combined Variation (B)</p> Signup and view all the answers

What is the first step Nezuko should take to simplify the expression $\sqrt{3}(\sqrt{6} - 2\sqrt{6})$?

<p>Simplify $\sqrt{6} - 2\sqrt{6}$ first. (A)</p> Signup and view all the answers

Which is the correct order of steps to simplify the expression $\frac{\sqrt{98x^{3}y^{5}}}{\sqrt{2x}} - 3\sqrt{x^{5}y}$?

<p>Simplify both terms and then apply the subtraction. (A)</p> Signup and view all the answers

What happens to the expression $- 3\sqrt{18} + 3\sqrt{8} - \sqrt{24}$ after simplification?

<p>It results in $3\sqrt{2} - 2\sqrt{6}$. (D)</p> Signup and view all the answers

Is Tanjiro correct in his procedure for simplifying the expression $\frac{\sqrt{3} + 2}{\sqrt{3} - 2}$ resulting in $- 7 - 4\sqrt{3}$?

<p>No, he should have obtained a positive result. (B)</p> Signup and view all the answers

Was the architect's process for calculating the area of the circular garden correct when using $\pi r^2$ with $r = \frac{5\sqrt{2}}{2}$?

<p>Yes, the process was correct and concise. (A)</p> Signup and view all the answers

If the area of the playground is 64 square meters, what should be the first step to find the length of the mesh net required?

<p>Get the square root of 64. (B)</p> Signup and view all the answers

After simplifying $\sqrt{3}(\sqrt{27} - \sqrt{3})$, what is the simplified form?

<p>$3\sqrt{3} - 3$. (A)</p> Signup and view all the answers

In the expression $\frac{\sqrt{18} - \sqrt{8}}{\sqrt{2}}$, what should be done first to simplify it?

<p>Simplify each square root separately. (C)</p> Signup and view all the answers

Flashcards

Inverse Variation

A relationship between two variables where one variable increases as the other decreases, and their product remains constant.

Direct Variation

A relationship between two variables where one variable increases as the other increases, and the ratio between them remains constant.

Combined Variation

A relationship between variables where one variable changes based on the combined effect of multiple variables, either directly or inversely.

Joint Variation

A special type of combined variation where one variable varies directly with more than one variable.

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Constant of Variation

A fixed number which represents the relationship between variables in direct or inverse variation.

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Force varies jointly with mass and acceleration

The force needed to move an object is directly proportional to its mass and acceleration.

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Variable 'N' varies inversely as 'M'

As the value of one variable increases, the other variable decreases in a way that their product is constant.

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If force is doubled (mass constant) what happens to acceleration?

If the force is doubled, while the mass remains the same, the acceleration also doubles.

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Exponent of zero

Any non-zero number raised to the power of zero equals one.

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Negative exponent

A negative exponent indicates the reciprocal of the base raised to the positive value of the exponent.

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Power of a power

When raising a power to another power, multiply the exponents.

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Simplify ( (4x^-3y^-4) / (7x^-5y^0) )^0 )^-1

The expression simplifies to 1. Any non-zero number raised to the power of zero is 1. The whole expression simplifies to 1 raised to -1, which is still 1.

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Pythagorean theorem

In a right triangle, the square of the hypotenuse (longest side) is equal to the sum of the squares of the other two sides.

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Finding Yor's distance from Anya's school

Use the Pythagorean theorem to find the diagonal distance between Yor's house and Anya's school. The distance between the house and the grocery store and the distance between the grocery store and the school form the two sides of a right triangle.

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Rational exponents

Exponents that are fractions. The numerator represents the power, and the denominator represents the root.

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Simplify (64x^8)^(1/6)

Using the laws of exponents, the expression simplifies to 2x^(4/3).

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Simplify [$a^{\frac{3}{2}}*a^{\frac{5}{4}}/a^{\frac{1}{4}}$]{.math.inline}

Combine the terms with the same base by adding their exponents and simplify the result.

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[$\left( \frac{16x^{12}}{81y^{4}}\right)^{\frac{3}{4}}$]{.math.inline} Simplify

Apply the power of a quotient rule: (a/b)^n = a^n / b^n. Then simplify each term by distributing the exponent and reducing the resulting exponents.

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Simplify [$\frac{3m^{- 4}n^{2}}{15m^{- 3}n^{- 2}}$]{.math.inline}

Apply the rule of negative exponents: a^-n = 1/a^n. Then simplify the fractions and combine like terms with common base.

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Simplify [$\sqrt[3]{40x^{5}y^{7}}$]{.math.inline}

Find the cube root of the coefficient, and simplify the variables by dividing their exponents by 3.

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Simplify [$\frac{\sqrt{75x^{4}}}{\sqrt{3x}}$]{.math.inline} Efficiently

Combine the terms under one square root by using the rule: a / b = (a/b). Simplify the resulting expression.

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Is [$\sqrt{\frac{8}{7}}$]{.math.inline} simplified?

No, because the 8 has a perfect square factor (4) that can be simplified further.

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Simplify [$\sqrt[4]{128a^{12}b^{17}}$]{.math.inline}

Find the fourth root of the coefficient. Simplify the variables by dividing their exponents by four.

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Simplify [$\sqrt[4]{81x^{12}y^{8}}$]{.math.inline} Efficiently

Jimin's approach is more efficient because grouping terms into fourth powers minimizes steps, allowing for direct simplification.

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Simplify [$\sqrt{3}(\sqrt{27} - \sqrt{3})$]{.math.inline}

To simplify this expression, first simplify the terms inside the parenthesis, then multiply by [$\sqrt{3}$]{.math.inline}. [$\sqrt{27} = 3\sqrt{3}$]{.math.inline}, so the expression becomes [$\sqrt{3}(3\sqrt{3} - \sqrt{3})$]{.math.inline}, which simplifies to [$\sqrt{3}(2\sqrt{3}) = 6$]{.math.inline}.

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Nezuko's first step

Nezuko's first step in simplifying [$\sqrt{3}(\sqrt{6} - 2\sqrt{6})$]{.math.inline} should be to subtract the terms inside the parentheses. [$\sqrt{6} - 2\sqrt{6} = -\sqrt{6}$]{.math.inline}, so the expression becomes [$\sqrt{3}(-\sqrt{6}) = -\sqrt{18}$]{.math.inline}.

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Simplifying the expression [$\frac{\sqrt{98x^{3}y^{5}}}{\sqrt{2x}} - 3\sqrt{x^{5}y}$]{.math.inline}

The correct order of steps is: 1. Simplify the first term. 2. Simplify the second term. 3. Subtract the simplified terms.

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Simplifying [$-3\sqrt{18} + 3\sqrt{8} - \sqrt{24}$]{.math.inline}

To simplify, break down the radicals into their prime factors. [$\sqrt{18} = 3\sqrt{2}$]{.math.inline}, [$\sqrt{8} = 2\sqrt{2}$]{.math.inline}, and [$\sqrt{24} = 2\sqrt{6}$]{.math.inline}. Substitute these back into the original expression, then combine like terms: [$-9\sqrt{2} + 6\sqrt{2} - 2\sqrt{6} = -3\sqrt{2} - 2\sqrt{6}$]{.math.inline}.

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Tanjiro simplifying [$\frac{\sqrt{3} + 2}{\sqrt{3} - 2}$]{.math.inline}

Tanjiro is incorrect. While multiplying the numerator and denominator by [$\sqrt{3} + 2$]{.math.inline} rationalizes the denominator, it leads to a negative result. He should have multiplied by [$\sqrt{3} + 2$]{.math.inline} (the conjugate of the denominator).

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The architect's process

The architect correctly calculated the area of the circular garden, using the correct formula and the radius from the diameter. The radius of the garden is [$\frac{\sqrt{50}}{2} = \frac{5\sqrt{2}}{2}$]{.math.inline}, and the area is calculated as [$\pi (\frac{5\sqrt{2}}{2})^2 = \frac{25\pi}{2}$]{.math.inline}.

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First step to find the mesh net length

The first step is to find the length of one side of the square playground since the area of a square is side * side. To find the length of a side, you need to find the square root of the area. The square root of 64 is 8, so the length of one side of the square playground is 8 meters.

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What is the mesh net length?

The mesh net length needed to enclose the 8 meter by 8 meter square playground is 32 meters. 8 meters for each side of the square, times 4 sides, equals 32 meters.

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Study Notes

Mathematics 9 - Variation & Equations

  • Variation Types:

    • Direct Variation: One variable increases as the other increases, or one decreases as the other decreases. A directly proportional relationship is represented by the equation y = kx.
    • Inverse Variation: One variable increases as the other decreases, or one decreases as the other increases. An inversely proportional relationship is represented by the equation y = k/x.
    • Joint Variation: More than two variables are involved. One variable changes in proportion to the product of other variables.
    • Combined Variation: A combination of direct and inverse variation.
  • Relationships between Variables:

    • The cost of a product varies directly with the price of production.
    • The profit varies jointly with the number of items sold and the selling price per item.
  • Formulas & Statements:

    • y = kx/z: y is directly proportional to x and inversely proportional to z.
    • y is directly proportional to x and z: y = kxz.
    • N varies directly as M: N = 5M.
    • N varies inversely as M: NM= 5
  • Simplifying Expressions

    • Use order of operations (PEMDAS/BODMAS) when simplifying expressions.
    • Simplify expressions using laws of exponents: xa * xb = xa+b; xa / xb = xa-b; (xa)b = xab*. Be careful with negative exponents.
  • Problem Solving: Word problems often translate into equations. Identify the variables and their relationships (i.e. directly, inversely, or jointly) to find an appropriate equation. Solve for the unknown variables.

  • Example Problems

    • Calculating rates: Given force, mass and acceleration to calculate mass, if acceleration or force changes.
    • Simplifying expressions such as: -3√18+3√8-√24
    • Solving for missing sides.
  • Special Cases:

    • A variable raised to the zero power equals 1. This should be highlighted.
    • A variable raised to a negative power is reciprocated.

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