Question

find the maximum y value on the graph y=f(x)

f(x)=-x^2=8x+6

Answer 1

@vortish f(x) = -x^2 = 8x+6 ??????? is it right?

Answer 2

no it is f(x)=-x^2+8+6

Answer 3

ok take the first derivative of f(x) and put the derivative equal to zero
and tell me what u r getting?

Answer 4

i dont understand that can you draw it and then i will be understand what your asking pls

Answer 5

cool it is given f(x) = -x^2+8x+6
can u do the differentiation of f(x) w.r.t x ?

Answer 6

no I always had trouble with these expressions

Answer 7

fine as we know d/dx ( x^n) = n x^(n-1) and d/dx(constant) = zero
so f ' (x) = -2x+8
did u follow this step?

Answer 8

yup

Answer 9

now put f '(x) = o and tell me what is the value of x u r getting?