Math Problem Statement

Lillian graphed a linear function through the points (‒7, ‒4) and (7, 6). What are the slope and y-intercept of the graph?

A.The slope is 57 , and the y-intercept is ‒1. B.The slope is 57 , and the y-intercept is 1. C.The slope is 75 , and the y-intercept is ‒1. D.The slope is 75 , and the y-intercept is ‒1.

Solution

To solve for the slope and y-intercept of the linear function passing through the points (7,4)(-7, -4) and (7,6)(7, 6), let's follow these steps:

Step 1: Find the Slope

The formula for the slope mm of a line passing through two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Substituting the given points (7,4)(-7, -4) and (7,6)(7, 6):

m=6(4)7(7)=6+47+7=1014=57m = \frac{6 - (-4)}{7 - (-7)} = \frac{6 + 4}{7 + 7} = \frac{10}{14} = \frac{5}{7}

So, the slope mm is 57\frac{5}{7}.

Step 2: Find the Y-intercept

The equation of a line in slope-intercept form is:

y=mx+by = mx + b

Where mm is the slope and bb is the y-intercept. We can use one of the points and the slope to solve for bb.

Using the point (7,4)(-7, -4):

4=57(7)+b-4 = \frac{5}{7}(-7) + b

Simplify and solve for bb:

4=5+b    b=4+5=1-4 = -5 + b \implies b = -4 + 5 = 1

So, the y-intercept bb is 11.

Conclusion

The correct answer is: B. The slope is 57\frac{5}{7}, and the y-intercept is 1.

Would you like further details or have any questions?

Here are 5 related questions:

  1. How would you find the equation of the line given a different set of points?
  2. Can you explain why the slope formula works?
  3. How do you convert between different forms of a linear equation?
  4. What does the slope represent in a real-world context?
  5. How can you graph a line using its slope and y-intercept?

Tip: Remember that the y-intercept is where the line crosses the y-axis, which means x=0x = 0 at that point.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Functions
Slope-Intercept Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Slope-intercept form: y = mx + b

Theorems

Slope formula

Suitable Grade Level

Grades 8-10