Find the equation of the line in slope-intecept form passing through the point (-9,-9) but perpendicular to the line: 7x−5y=25

Answer 1

7x-5y = 25

-5y = -7x +25

y = 7x/5 -5 with slope = 7/5 = the coefficient of the x term when the linear equation is solved for y

a perpendicular line has a negative inverse slope =-5/7

just take 7/5, flip it upside down and change its sign

y =-5x/7 + b

plug in x = -9, y=-9 to solve for b=y intercept

-9=-5(-9)/7 + b

b =-9 -45/7 = -108/7

y= (-5/7)x - 108/7 is the perpendicular line through (-9,-9) in slope intercept form

it may help to graph the two lines and plot the point (-9,-9)