First see you can factor out 4. What is left is x^2 + 6x - 16.
That can be factored as (x+8)(x-2) so the total factorization is
4(x+8)(x-2)
First off all, let's find

.
This shows that Bai found the correct quotient.
If

, then

. Using this rule, you have to check that

is equal to product

.
Thus, Bai checked his work using multiplication correctly.
Answer: Correct choice is A.
Remember: Please Excuse My Dear Aunt Sally (PEMDAS)
In solving algebraic expressions, there is an order in which to solve it.
<span>1) perform the operation inside the </span>parenthesis<span> first </span>
<span>2) then perform the operation with the </span>exponents
<span>3) apply </span>multiplication<span> and </span>division<span> from left to right of the equation.</span>
<span>4) apply </span>addition<span> and </span>subtraction<span> from left to right of the equation.</span>