Answer
The answers are below.
Work Step by Step
a) John forgot that you cannot just distribute the negative and square both terms. The answer actually should be: $x^2 + 8x + 16$.
b) While John considered the middle term this time, he forgot that he has to add the -5x to itself, for there are two -5x terms. The answer actually should be: $x^2 -10x +25$.
c) John forgot that -6 times -6 is positive 36. The answer actually should be: $x^2 -12x +36$.
d) John forgot that when multiplying 3x by 3x, the threes must be multiplied by each other. The answer actually should be: $9x^2 + 12x+4$.
e) John added the ones instead of multiplying. The answer actually should be: $x^2 + 2x + 1$.
f) John forgot that since it is x-3, it is -6x and not +6x. The answer actually should be: $x^2 -6x + 9$.
