I got this wrong on my test and just need the right answer to work the problem backwards and figure it out.
1) If the graph of y = -4x + 7 is perpendicular to the graph of y = mx + 3 , then what does m equal?
-4 (wrong)
4 (wrong)
1/4
-1/4

Question

I got this wrong on my test and just need the right answer to work the problem backwards and figure it out. 
1) If the graph of y = -4x + 7 is perpendicular to the graph of y = mx + 3 , then what does m equal? 
       -4 (wrong)
       4   (wrong)
       1/4
       -1/4

anonymous · Answer

hint... if two lines $$y=m_1x+b_1\text{ and }y=m_2x+b_2\text{ are perpendicular, then } m_1\cdot m_2=-1$$

anonymous · Answer

so  -1/4?

anonymous · Answer

no... (-4)(-1/4)=1

anonymous · Answer

I'll never use this type of math again so I guess it doesn't matter but thank you.

anonymous · Answer

you never know...

anonymous · Answer

but i bet you'll have to follow directions or apply a principle.  same thing here.

anonymous · Answer

nah, this math is pretty much useless unless you're going to be a rocket scientist or math teacher.  I think that's why adults are so dumb...wish I could learn real world math like accounting.  Anyway, thanks.

anonymous · Answer

okay einstein... good luck (you'll need it)

anonymous · Answer

believe me i know...i suk at math but I'll be the one handing out speeding tickets and arresting wife beaters! : )