ALGEBRA
posted by Anonymous on .
Lines A and B are perpendicular and have the same xintercept. The equation of line A
is x + 2y  4 = 0 . Determine the yintercept of line B.
A.8
B.2
C. 4
D. 8
This is the work that I did:
x + 2y  4 = 0
+4 +4
x+2y = 4
x x
2y = x+4
divide both sides by 2
and I got 1/2x+2
I thought that the answer would be 2 maybe but its 8. How is it 8?

x + 2y  4 = 0
x + 2y = 4
to find xintercept, y = 0
x + 2(0) = 4
x = 4
xintercept = (4.0)
slope intercept form (which you got right above) y = mx + b
for Line A is y = 1/2 x + 2
slope m = 1/2
If two lines are perpendicular, the slope of one is the negative reciprocal of the slope of the other.
Slope of Line B = ?
Line B through point (4,0)(line A and B have the same xintercept)
To write equation of Line B
plug slope m in y = mx + b, and use point (4,0) to solve for b, which is the yintercept.