Quadratic Equations: Standard Form

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Questions and Answers

Which of the following equations is NOT a quadratic equation?

  • $9x - 2 = 0$ (correct)
  • $x^2 + 4 = 0$
  • $2x^2 - 5x = 0$
  • $5x^2 - 3x + 7 = 0$

In the quadratic equation $7x^2 - 9x + 2 = 0$, what are the values of a, b, and c, respectively?

  • a = 7, b = 9, c = 2
  • a = -7, b = -9, c = 2
  • a = 7, b = -9, c = -2
  • a = 7, b = -9, c = 2 (correct)

Which term is missing in the quadratic equation $4x^2 - 16 = 0$?

  • Constant term
  • All terms are present
  • Quadratic term
  • Linear term (correct)

Rewrite the equation $3x^2 + 5x = 8$ in standard form and identify the values of a, b, and c.

<p>$3x^2 + 5x - 8 = 0$; a = 3, b = 5, c = -8 (C)</p> Signup and view all the answers

Given the equation $-2x^2 + 6x - 4 = 0$, what is the standard form of the equation after ensuring 'a' is positive?

<p>$2x^2 - 6x + 4 = 0$ (A)</p> Signup and view all the answers

Which of the following is the standard form of the equation $5x(x - 3) = 15$?

<p>$5x^2 - 15x - 15 = 0$ (A)</p> Signup and view all the answers

What are the values of a, b, and c in the standard form of the expanded equation $(x + 4)(x - 2) = 5$?

<p>a = 1, b = 2, c = -13 (C)</p> Signup and view all the answers

If $a = 0$ in the general quadratic equation $ax^2 + bx + c = 0$, what type of equation does it become?

<p>Linear equation (B)</p> Signup and view all the answers

Which of the following modifications will NOT change the nature of a quadratic equation?

<p>Multiplying the entire equation by -1 (C)</p> Signup and view all the answers

Which of the following equations, when simplified and written in standard form, has $a = 5$, $b = -3$, and $c = 0$?

<p>$5x^2 - 3x = 0$ (B)</p> Signup and view all the answers

If a quadratic equation is given as $x^2 + kx + 9 = 0$ and $k = 0$, what is a, b, and c?

<p>a=1, b=0, c=9 (C)</p> Signup and view all the answers

Determine a, b, and c for the quadratic equation: $2x(x+3) = -4x + 7$

<p>a=2, b=10, c=-7 (C)</p> Signup and view all the answers

Identify a, b, and c in standard form: $(4x - 3)(x + 2) = 3(x - 1)$

<p>a=4, b=5, c=-3 (C)</p> Signup and view all the answers

After expressing the equation in standard form, which equation has a = 7, b = -1/3, and c = 0?

<p>7x^2= 1/3x (B)</p> Signup and view all the answers

What type of equation is described by 3x + 5 = 0?

<p>Linear Equation (C)</p> Signup and view all the answers

What values of a, b, and c describe the following equation: $-x^2 + 5x = 10$?

<p>a=-1, b=5, c=-10 (D)</p> Signup and view all the answers

What equation represents a quadratic equation where a = 4, b = 0, and c = -25?

<p>4x^2 - 25 = 0 (B)</p> Signup and view all the answers

What adjustment should be made to ensure positive values for 'a' in the equation $-3x^2 + 6x - 9 = 0$?

<p>Multiply by -1 (A)</p> Signup and view all the answers

What makes the equation a quadratic equation?

<p>Presence of a second-degree exponent (B)</p> Signup and view all the answers

How does expanding $4x^2 + 8x - 12 = 0$ by a factor of two affect its values?

<p>Does not affect the roots (D)</p> Signup and view all the answers

Flashcards

Quadratic Equation

A mathematical sentence of the second degree (highest exponent of the variable is 2).

Standard Form

The standard form of a quadratic equation is ax² + bx + c = 0, where a, b, and c are real numbers and a ≠ 0.

Quadratic Term

The term 'ax²' in the standard form of a quadratic equation (ax² + bx + c = 0).

Linear Term

The term 'bx' in the standard form of a quadratic equation (ax² + bx + c = 0).

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Constant Term

The term 'c' in the standard form of a quadratic equation (ax² + bx + c = 0); it's a number without a variable.

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Identifying a, b, and c

Rearrange the equation to the form ax² + bx + c = 0, then identify the numerical coefficients and the constant.

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Write in Standard Form

Rewrite the equation in the form ax² + bx + c = 0 by moving all terms to one side.

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Positive 'a' Value

If 'a' is negative, multiply the entire equation by -1 to make 'a' positive while keeping the equation balanced.

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Expanding Expressions

Expand any expressions, simplify, and then rearrange to the standard form ax² + bx + c = 0 to identify a, b, and c.

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Defining Characteristic

The presence of x² (a second-degree term) is essential; if a = 0, the equation is not quadratic. If b or c = 0, it remains a quadratic equation.

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Study Notes

Quadratic Equations

  • A quadratic equation in one variable is a mathematical sentence of the second degree.
  • Second degree indicates that the highest exponent of the variable is 2.
  • Quadratic equations can be written in standard form: ax² + bx + c = 0.
  • a, b, and c are real numbers.
  • a should not be equal to zero.
  • a should be a positive real number.

Parts of a Quadratic Equation (in standard form)

  • ax² is the quadratic term.
  • bx is the linear term.
  • c is the constant term.

Identifying a, b, and c in a Quadratic Equation

  • Arrange the equation into standard form first
  • Example: x² - 5x + 3 = 0
  • a = 1 (numerical coefficient of x² is 1)
  • b = -5
  • c = 3
  • Example: 9r² - 25 = 0
  • a = 9
  • b = 0 (missing linear term)
  • c = -25

Writing a Quadratic Equation in Standard Form

  • Start with a quadratic equation in the form ax² + bx + c = 0
  • Example: x² + x = 4
  • Rewrite as: x² + x - 4 = 0
  • a = 1, b = 1, c = -4
  • Example: 7x² = ⅓x
  • Rewrite as: 7x² - ⅓x = 0
  • a = 7, b = -⅓, c = 0
  • Example: 6x² = 9
  • Rewrite as: 6x² - 9 = 0
  • a = 6, b = 0, c = -9
  • If 'a' is negative, multiply or divide the entire equation by -1 to make 'a' positive
  • Example: -8x² + x = 6
  • Rewrite as: -8x² + x - 6 = 0
  • Multiply by -1: 8x² - x + 6 = 0
  • a = 8, b = -1, c = 6

Special Cases and Twists

  • Example: 3x(x - 2) = 10
  • Expand: 3x² - 6x = 10
  • Rewrite in standard form: 3x² - 6x - 10 = 0
  • a = 3, b = -6, c = -10
  • Example: (2x + 5)(x - 1) = 6 (product of two binomials)
  • Expand: 2x² - 2x + 5x - 5 = 6
  • Simplify: 2x² + 3x - 5 = 6
  • Rewrite in standard form: 2x² + 3x - 5 - 6 = 0
  • Combine constants: 2x² + 3x + 1 = 0
  • a = 2, b = 3, c = 1

Key Considerations

  • If a = 0, the equation is not quadratic (it becomes a linear equation).
  • If b = 0, the equation is still quadratic as long as 'a' and 'c' exist.
  • If c = 0, the equation is still quadratic as long as 'a' exists.
  • The defining characteristic of a quadratic equation is the presence of a second-degree exponent.

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