Algebra Class: Key Equations and Concepts

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Questions and Answers

Solve −4(2x − 1) = −6(x + 2) − 2.

9

Rearrange the formula C = 2Ï€r to solve for r.

r = C/2Ï€

Solve −2x − 13 = 8x + 7.

-2

Solve 4x − 9 = 15.

<p>6</p> Signup and view all the answers

Given the equation 3x − 3 = 6x + 1, select the reasoning that correctly solves for x.

<p>Subtract 1, subtract 3x, then divide by 3.</p> Signup and view all the answers

Solve x/4 = 8.

<p>32</p> Signup and view all the answers

Solve −5x = 30.

<p>-6</p> Signup and view all the answers

In order to solve the equation −3x + 6 = 5, what is the first step?

<p>Subtract 6 from both sides.</p> Signup and view all the answers

Let f(x) = x^2 − 3x − 7. Find f(−3).

<p>11</p> Signup and view all the answers

Let f(x) = 5x + 12. Find f^−1(x).

<p>x - 12/5</p> Signup and view all the answers

Let f(x) = 12/4 x + 2. Find f(−1).

<p>-6</p> Signup and view all the answers

Let f(x) = 9x − 2 and g(x) = −x + 3. Find f(g(x)).

<p>-9x + 25</p> Signup and view all the answers

Let f(x) = x − 2 and g(x) = x^2 − 7x − 9. Find f(g(−1)).

<p>-3</p> Signup and view all the answers

Let f(x) = 2x − 6. Solve f^−1(x) when x = 2.

<p>4</p> Signup and view all the answers

On the graph of the equation x - 4y = -16, what is the value of the y-intercept?

<p>4</p> Signup and view all the answers

For the functions f(x) = 2x + 2 and g(x) = 7x + 1, which composition produces the greatest output?

<p>g(f(x)) produces the greatest output.</p> Signup and view all the answers

Which of the following expressions represents a function: {(1, 2), (4, -2), (8, 3), (9, -3)}?

<p>True</p> Signup and view all the answers

Consider the function f(x) = 8 − 3x^2. Find the value of f(x) when x = 3.

<p>-19</p> Signup and view all the answers

Given the function f(x) = 3x + 4, which of the following expressions is the inverse?

<p>y = (x - 4)/3</p> Signup and view all the answers

A.Given the equation 2(3x − 4) = 5x + 6, solve for the variable. What is Charlie's solution?

<p>Charlie is incorrect. His answer should be x = 1/2.</p> Signup and view all the answers

If the linear function representing the amount of rainfall each week is f(w) = 2.5w + 3, what does the 3 represent in this function?

<p>The amount of rainfall in week 0</p> Signup and view all the answers

What type of line is the graph of 4x + y = −3?

<p>Falling</p> Signup and view all the answers

What is the slope of the line between (3, −4) and (−2, 1)?

<p>-1</p> Signup and view all the answers

What is the slope of the line y = 3?

<p>0</p> Signup and view all the answers

What is the slope of the line between (-4, 4) and (-1, -2)?

<p>-2</p> Signup and view all the answers

What is the slope of the line that passes through (2, 12) and (4, 20)?

<p>4</p> Signup and view all the answers

What is the equation of a horizontal line passing through the point (−7, 5)?

<p>y = 5</p> Signup and view all the answers

Given the equation 4x − 26 = 2x − 4, what order of operations completely solves for x?

<p>Subtract 2x, then add 26, lastly divide by 2.</p> Signup and view all the answers

Which function has the largest slope?

<p>g(x)</p> Signup and view all the answers

Given that f(x) = 2x + 1 and g(x) = −5x + 2, solve for f(g(x)) when x = 3.

<p>-25</p> Signup and view all the answers

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Study Notes

Key Equations and Concepts

  • Circumference of a Circle: C = 2Ï€r; rearranged to solve for radius: r = C/2Ï€.
  • Common Linear Equation Forms:
    • Slope-Intercept Form: y = mx + b, where m is the slope and b is the y-intercept.
    • Point-Slope Form: y - y1 = m(x - x1), used when a point and slope are known.

Solving Linear Equations

  • Typical solving strategy: isolate the variable through addition, subtraction, multiplication, or division.
  • Example: -4(2x − 1) = −6(x + 2) − 2 results in x = 9.
  • Example: From -2x − 13 = 8x + 7, deduced x = -2.

Functions and Their Inverses

  • For a function f(x) = ax + b, the inverse process involves swapping x and y, leading to f^−1(x).
  • Example: f(x) = 2x + 2; solving f^−1(x) gives x = 4.
  • Composition of functions: f(g(x)) requires evaluating the outer function at the result of the inner function.

Graphing and Slopes

  • Slope Calculation: The slope between two points (x1, y1) and (x2, y2) is m = (y2 - y1) / (x2 - x1).
  • Example: Slope between (3, -4) and (-2, 1) is -1.
  • Horizontal line has a slope of 0; vertical line is undefined.

Linear Models in Context

  • Example: A function representing rainfall f(w) = 2.5w + 3 indicates that 3 is the baseline rainfall before week 1.
  • Example: Alex saves money modeled by M = 6h + 2, denoting initial savings and rate of saving.

Errors and Reasoning in Problem Solving

  • Identifying mistakes in calculations is crucial. Example: Aaron erred by subtracting incorrectly in solving the equation.
  • Understanding the order of operations and justifying each step is essential for accurate results.

Special Function Characteristics

  • Functions like f(x) = x^2 + 3x + 6 can yield specific outputs for given x-values through substitution.
  • Ensure that the range for practical functions, such as the number of text messages sent, only includes integers.

Application Problems

  • Real-world problems, like Joe's earnings model, combine fixed rates and variable conditions to derive total outcomes.
  • A fish tank model (F = 0.4P) helps quantify relationships between variables such as fish count and plant presence.

Visual Characteristics of Graphs

  • A falling line indicates a negative slope, such as x = -5, which is a vertical line.
  • The y-intercept is often determined by substituting x = 0 in the equation.

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