Question

The equation of line q is 5y - 4x = 10. Write an equation of the line that is perpendicular to q and passes through the point (-15, 8)

Answer 1

5x + 4y + 43 = 0

Step-by-step explanation:

y=mx+b

m=slope

b=y intercept

perpendicuar lines have slopes that multiply to get -1

so

solving for y

add 4x both sides and divide by 5 to get

y=4/5x+2

slope is 4/5

perpendicular means the slopes multiply to get -1

so

4/5 times what=-1?

what=-5/4

so

y=(-5/4)x+b

find b

given the point (-15,8)

8=(-5/4)(-15)+b

8=75/4+b

-43/4=b

y=(-5/4)x-43/4

convert to standard form:

5x + 4y + 43 = 0

Answer 2

y = -5/4x - 10.75

Step-by-step explanation:

First, put the equation in slope intercept form by isolating y:

5y - 4x = 10

5y = 4x + 10

y = 4/5x + 2

Perpendicular lines have opposite reciprocal slopes, so the slope will be -5/4

Plug in the slope and the given point into y = mx + b to find b:

y = mx + b

8 = -5/4(-15) + b

8 = 18.75 + b

-10.75 = b

Plug in the slope and y intercept into y = mx + b

y = mx + b

y = -5/4x - 10.75