Question

Ok, i need a second opinion: find the maximum y value on the graph of y=f(x)

f(x)=-x^2+8x+10.

my answer is y=58....am i right?

Answer 1

f'(x) = -2x + 8
0 = -2x + 8
x = 4

so

f(4) = -(4)^2 + 8(4) + 10 = 58

Answer 2

sweet, so i was right?

Answer 3

yase

Answer 4

Oops.

-4^2 = -16

The max is 26.