Question

Consider line A whose equation is y = -10x + 8. If line B is perpendicular to line A and has a y-intercept at y = 3, what is the equation for line B?

Answer 1

The equation of line B is

y = 3x + 3

Explanation:

The equation of line A is y = -10x + 8.

Recall, the slope intercept equation is y= mx + c

Where m is slope

c = intercept

Comparing the equation of line A with the slope intercept equation,

Slope, m = -10

For two lines that are perpendicular, the product of their slopes is -1

Let slope of line B = m1

Since line A and line B are perpendicular,

m×m1 =-1

-10 × m1 = -1

m1 = -1/-10= 1 / 10

The y- intercept of line B is 3

We will make use of the slope intercept equation again

y = mx + c

With m = 1/10

c = 3

y = 3x + 3

The equation of line B is

y = 3x + 3