Question

Identify the min/max value y=2(x-4)(x+7)

Answer 1

Y=2x-8+2x+14=4x+6

Answer 2

Y=4x+6

Answer 3

because this function is of a second degree we know it's graph should be a Parabolic one. now because the Coefficient of the X^2 is positive we know that she's "smiling" (the Parabola is in U shape). so now we know that we're looking for a min point. we know that the Parabola is touching the x axis in the points (-7,0) and (4,0) because: x-4=0 --> x=4 and x+7=0 --> x=-7.
the middle point between the two is (-1.5,0).
insert this point to the original function and you'll get the the Y parameter.

Answer 4

if you know how to use Derivatives, just expend the brackets, find f'(x).
now take f'(x) and equalize to zero. take the x that you found and place it in the original function and you'll get the Y.

Answer 5

if my calculation is correct you should get a Min point at (-1.5,60.5)