which equation represents the line that contains the point (-2,9) and is perpendicular to the line y=2x+6?
A.y=-1/2x-7 B.y=-1/2x+8 C.y=-1/2x+11 D. y=2x+13

Question

which equation represents the line that contains the point (-2,9) and is perpendicular to the line y=2x+6?
A.y=-1/2x-7 B.y=-1/2x+8 C.y=-1/2x+11 D. y=2x+13

anonymous · Answer

help please

mww · Answer

You can use the point-gradient formula. 
$$y - y1 = m(x -x1)$$
The point would be the one you were given and the gradient is the one that would make it perpendicular to y = 2x + 6.
(Use the fact that $$m1 \times m2 = -1$$ if the lines are perpendicular.)
Once you find the gradient, plug in all the vaues into the formula.

anonymous · Answer

your looking for a perpendicular line which means the slope will be the negative inverse of the slope of your given equation. Since that slope is 2, then the perpendicular slope will be -1/2.
Now we use y - y1 = m(x - x1) using slope -1/2 and points (-2,9)
lets sub our info in...
y - 9 = -1/2(x -(-2)
y - 9 = -1/2x + 2
y = -1/2x + 2 + 9
y = -1/2x + 11 <-- answer C