A student estimated the sum

7.95 + 8.11 + 78.5 + 8.05 + 79.4 + 0.815 as:

All the numbers begin with a 7 or 8, so use cluster estimation.
8 + 8 + 80 + 8 + 80 + 0.8 = 184.8

Explain why this reasoning is not accurate

7

step-by-step explanation:

the answer would be 7

the answer is a if my teacher taught me correct

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