If f ( x ) f ( x ) is a linear function, f ( − 5 ) = 0 f ( - 5 ) = 0 , and f ( 2 ) = 4 f ( 2 ) = 4 , find an equation for f ( x ) f ( x ) f(x)=

Explanation:

We have

f(-5) = 0 and f(2) = 4

This means the two points (-5,0) and (2,4) are on this line

Find the slope of the line through (x1,y1) = (-5,0) and (x2,y2) = (2,4)

m = (y2 - y1)/(x2 - x1)

m = (4 - 0)/(2 - (-5))

m = (4 - 0)/(2 + 5)

m = 4/7 is the slope

Plug m = 4/7 and (x1,y1) = (-5,0) into the point-slope formula. Solve for y.

y - y1 = m(x - x1)

y - 0 = (4/7)(x - (-5))

y = (4/7)(x + 5)

y = (4/7)x + (4/7)*5

y = (4/7)x + 20/7

f(x) = (4/7)x + 20/7

This linear equation has a slope of 4/7 and a y intercept of 20/7.