Answer:
6.25
Step-by-step explanation:
M = -4 -4 / 5- 3 = -8/2 = -4
y = -4x + b
4 = -12 + b
b = 16
y = -4x + 16
Check the picture below. Recall, is an open-top box, so, the top is not part of the surface area, of the 300 cm². Also, recall, the base is a square, thus, length = width = x.

so.. that'd be the V(x) for such box, now, where is the maximum point at?

now, let's check if it's a maximum point at 10, by doing a first-derivative test on it. Check the second picture below.
so, the volume will then be at
Answer:
x = -1, PR = 38.
Step-by-step explanation:
As Q is the midpoint of PR
PQ = QR
6x + 25 = 16 - 3x
9x = -9
x = -1.
PR
= 6x + 25 + 16 - 3x
= 6(-1) + 25 + 16 - 3(-1)
= -6 + 25 + 16 + 3
= 38.