Answer:
c
Step-by-step explanation:
Let the boat speed in still water be b.
Let the current speed be c.
The speed going upstream is 20/4 = 5 mph.
The speed going downstream is 32/4 = 8 mph.
b - c = 5 ........(1)
b + c = 8 .......(2)
Adding equations (1) and (2) we get:
2b = 13
b = 13/2 = 6.5
Plugging in the value for b into equation (1) we find c = 1.5.
The boat speed in still water is 6.5 mph and the current speed is 1.5 mph.
You have to square the binomial.
(x^3 + 4y) (x^3 + 4y)
Using FOIL:
x^9 + 4(x^3)y + 4(x^3)y + 16y^2
x^9 + 8(x^3)y + 16y^2
You could also use the formula: (a+b)^2 = (a^2 + 2ab + b^2).
