A and d seem correct to me.
b and c are definitely wrong.
Answer:
Factors: 
Step-by-step explanation:
We are given a polynomial:

We have to factor the given polynomial into its complex factors.
The factorization can be done as follows:

In the step after -6x+10=4x+20, he moved the terms incorrectly. you have to add 6x to both sides so it would be 10=4x+6x+20 which simplifies to 10=10x+20. subtract 20 from both sides to get -10=10x. divide both sides by 10. the answer is x=-1
5b^3 sq rt of a
There's not enough a's
I think it would the last one G