write the equation of a line that is perpendicularthat passes through the point (-6,8)

Question

write the equation of a line that is perpendicular to y=0.25x-7 and that passes through the point (-6,8)

Answer 1

^{The equation of  a line is:}

y = mx + b

 

If it is perpendicular to y = .25x - 7, the its slope (m) is the negative reciprocal of it.

Since y = .25x - 7 has a slope (m) of .25 (or 1/4), the slope of the perpendicular line is -4

 

Now we have:

y = -4x + b

 

Substitute point (-6,8) to find b;

 

8 = 24 + b

b = -16

 

The equation you are looking for is:

 

y = -4x - 16

 

 

Answer 2

y=0.25x-7

 

Slope of this line is .25; slope of perpendicular line is -4 (opposite sign and inverse)

 

substitute in coordinate values:

 

8 = -4 (-6) + b  (b is the new y intercept)

 

8 = 24 + b

 

b = -16

 

y = -4x - 16