Question

Find the equation of a line that has a slope of 4 and passes through the point (-1, 8).

(multiple choice)

A. y = -1x + 8

B. y = 4x + 4

C. y = 4x + 12

D. y = 4x

Answer 1

Slope intercept form: y=mx+b, with m being the slope and b being the y-intercept.

Plug 4 in for the slope, as that's given in the question:

y=4x+b

Now, we need to solve for the y-intercept, because the answer could be B, C, or D. You can do this by plugging in the given coordinate (-1,8) for x and y in the equation respectively.

8=4(-1)+b

Multiply.

8=-4+b

Add four to both sides.

12=b

The y-intercept is 12. Plug 12 into the equation for b:

y=4x+12 is the completed equation.

The answer is C.

I hope this helps :)