Intermediate Algebra

Question

A line is perpendicular to the line going through the points ( 2 , 8) and ( 8 , 5 ). The line goes though ( 6 , 8 ), what is the y-intercept (round to 1 decimal place)?

Answer 1

y = mx + b

The product of slopes of perpendicular lines is -1.

Slope of given line:

(5 - 8)/(8 - 2) = -3/6 = -1/2

Slope of perpendicular line:

m = -1/(-1/2) = 2

y = 2x + b

Use the given point to find b.

8 = 2(6) + b

b = -4

y = 2x - 4

The y-intercept is at (0,-4).