Question

If y = 2x - 8 , what is the minimum value of the product xy?
(A) -16
(B) -8
(C) -4
(D) 0
(E) 2

Answer 1

If you're not too busy, could you help me please?
@TuringTest @sourwing

Answer 2

minize x(2x-8)

Answer 3

what's that mean?

Answer 4

i meant minimize x(2x-8). Should be at the vertex

Answer 5

how do I minimize?
is it like find the derivative?

Answer 6

yes. But since this is a quadratic that opens up, you know the minimum is at the vertex

Answer 7

mmm
but how did you get
x(2x-8)
if the given equation was y = 2x - 8 ?

Answer 8

oh wait, I see it nvm

Answer 9

ok

Answer 10

so d/dx (x(2x-8)) = 4x - 8
and 4x-8=0 --> x = 2 ?

Answer 11

yes, what's y?

Answer 12

and what is xy?

Answer 13

mmm
y = 2(2) - 8 = -4
so xy = (2)(-4) = -8

ok got it now :) Thank You!