posted by AMY on .
Write an equation of the the line containing the given point and perpendicular to the given line. (7,-5); 9x+7y = 3.
What I have so far. y-9=(1/9(x-3). Not sure after this.
First of all the new slope should have been 7/9.
Now you have to use the given point this way ...
y + 5 = (7/9)(x-7)
multiply each side by 9 (I don't like fractions in my equations)
9y + 45 = 7x - 49
-7x + 9y = -93
7x - 9y = 93
A quick way to do the above..
If Ax + By = C is the equation , then
the line Bx - Ay = K is perpendicular to it,
if 9x + 7y = 3 is given , then
7x - 9y = k is the perpendicular line
sub in the given point ...
7(7) - 9(-9) = c = 93
7x - 9y = 93 is your new line