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College Algebra: Linear Equations, Slope, and Intercepts Study Guide

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Q13. Rewrite in slope-intercept form. Then state the zero (x-intercept) of the function.

Background

Topic: Linear Equations – Slope-Intercept Form and Intercepts

This question tests your ability to manipulate a linear equation into slope-intercept form () and to find the x-intercept (also called the zero) of the function.

Key Terms and Formulas:

  • Slope-intercept form: , where is the slope and is the y-intercept.

  • x-intercept (zero): The value of when .

Step-by-Step Guidance

  1. Start with the given equation: .

  2. Rearrange the equation to solve for in terms of (get $y$ by itself on one side).

  3. Once in form, identify the slope and y-intercept.

  4. To find the x-intercept, set in your equation and solve for .

Try solving on your own before revealing the answer!

Final Answer:

Rewriting in slope-intercept form:

Subtract from both sides:

Multiply both sides by :

Slope-intercept form:

To find the x-intercept, set :

The x-intercept (zero) is .

Q15. Which equation represents a line with slope and y-intercept $2$?

Background

Topic: Linear Equations – Identifying Slope and Intercept

This question tests your ability to recognize the equation of a line in slope-intercept form () given a specific slope and y-intercept.

Key Terms and Formulas:

  • Slope-intercept form:

  • Slope (): The coefficient of

  • y-intercept (): The constant term

Step-by-Step Guidance

  1. Recall that the equation of a line with slope and y-intercept is .

  2. Plug in and into the formula.

  3. Compare your result to the answer choices to find the matching equation.

Try solving on your own before revealing the answer!

Final Answer:

Plugging in the values, the equation is:

This matches answer choice B.

Q16. Which equation is parallel to and passes through ?

Background

Topic: Parallel Lines and Point-Slope Form

This question tests your understanding of parallel lines (same slope) and writing the equation of a line through a given point.

Key Terms and Formulas:

  • Slope of a line: For , slope is

  • Parallel lines: Have the same slope

  • Point-slope form:

Step-by-Step Guidance

  1. Find the slope of by rewriting in slope-intercept form or using .

  2. Since parallel lines have the same slope, use this slope for your new line.

  3. Use the point-slope form with the point and the slope you found.

  4. Simplify to slope-intercept form () and compare to the answer choices.

Try solving on your own before revealing the answer!

Final Answer:

The slope of is .

Using point-slope form:

Simplifying:

This matches answer choice A: .

Q17. Write the equation of the line that passes through and has slope $2$ in point-slope form and slope-intercept form.

Background

Topic: Writing Equations of Lines

This question tests your ability to use point-slope and slope-intercept forms to write the equation of a line given a point and a slope.

Key Terms and Formulas:

  • Point-slope form:

  • Slope-intercept form:

Step-by-Step Guidance

  1. Use the point-slope form with , , .

  2. Write the equation in point-slope form: .

  3. Expand and simplify to get the equation in slope-intercept form ().

Try solving on your own before revealing the answer!

Final Answer:

Point-slope form:

Slope-intercept form:

Q18. The equation is given. Find its slope, x-intercept, and y-intercept.

Background

Topic: Linear Equations – Slope and Intercepts

This question tests your ability to find the slope, x-intercept, and y-intercept of a line given in standard form.

Key Terms and Formulas:

  • Standard form:

  • Slope:

  • x-intercept: Set and solve for

  • y-intercept: Set and solve for

Step-by-Step Guidance

  1. Identify , , in the equation .

  2. Find the slope using .

  3. To find the x-intercept, set and solve for .

  4. To find the y-intercept, set and solve for .

Try solving on your own before revealing the answer!

Final Answer:

Slope:

x-intercept: (when )

y-intercept: (when )

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