Can someone please help me find b and c so that the parabola y=-3x^2+bx+c has vertex . (8,4)

Question

mertsj · Answer

Use vertex form and put in the vertex.  a = -3

hero · Answer

use x = -b/2a

mertsj · Answer

$$y=-3(x-8)^{2}+4$$

mertsj · Answer

Now rearrange the right side.

anonymous · Answer

so do i just solve for y

mertsj · Answer

$$y=-3(x ^{2}-16x+64)+4=-3x ^{2}-48x-188$$

mertsj · Answer

$$y=-3x ^{2}-48x-188$$

anonymous · Answer

OK, yea it worked for c=-188 but i put in b=-48 and it said inccorect, i was doing it the way you suggested but i cant seem to figure out what b is

mertsj · Answer

Oh gee.  -3 (-16x)= POSITIVE 48x   Sorry.

anonymous · Answer

yea i just got it, thanks so much

mertsj · Answer

yw

anonymous · Answer

theres also another problem, i think you were actually helping me out with it last week just wondering if you had time to help me again with it cant seem to figure it out