Question

HELP PLEASE
Consider the line -4x+9y=9
Find the equations of the line that is perpendicular & parallel to this line and passes through the points (3,-3)

Answer 1

@texaschic101

Answer 2

we need to find the slope of the line given so we will put it in y = mx + b form and m is the slope.
-4x + 9y = 9 -- add 4x to both sides
9y = 4x + 9 -- divide both sides by 9
y = 4/9x + 1
so the slope of this line is 4/9.

you understanding this so far ?

Answer 3

yes.. i got that far. i got y=4/9x+1 but then i couldnt figure out how to make it parallel and perpendicular. i tried using (3,-3) as the x & y.. but it wasnt working

Answer 4

a parallel line will have the same slope.... 4/9.
use y - y1 = m(x - x1)
slope(m) = 4/9
(3,-3) x1 = 3 and y1 = -3
now lets sub
y - (-3) = 4/9(x - 3)
y + 3 = 4/9x - 12/9
y = 4/9x - 12/9 - 3
y = 4/9x - 12/9 - 27/9
y = 4/9x - 39/9
y = 4/9x - 13/3 ==> parallel line

understand so far ?

Answer 5

yes!

Answer 6

a perpendicular line will have the negative reciprocal of the slope. Negative reciprocal of 4/9 is -9/4 (flip the slope and change the sign.
y - y1 = m(x - x1)
slope(m) = -9/4
(3,-3) x1 = 3 and y1 = -3
subbing tme
y - (-3) = -9/4(x - 3)
y + 3 = -9/4x + 27/4
y = -9/4x + 27/4 - 3
y = -9/4x + 27/4 - 12/4
y = -9/4x + 15/4 ==> your perpendicular line

Answer 7

any questions ?