How fast is the train traveling? A. 25 miles per hour
B. 50 miles per hour
C. 75 miles per hour
D. 100 miles per hour

10 b/c 5*2 =10

step-by-step explanation:

answer: x=60

hello from mrbilldoesmath!

answer:   x (x+6)^2, choice b

discussion:

factor x out of the equation:

x^3 + 12x^2 + 36x = x (x^2 + 12x + 36).

note that 6+6 = 12 and 6*6 = 36 so the above factors into:

x (x+6)^2

which is choice b

you,

mrb