Factor the common factor out of the expression (numbers that directly follow a variable are exponents)

Question

1. 10x2 + 2x - 5xy - y
2. -xz - 3yz + 4x + 12y
3. x2(y2 + 3) + 2(-3 - y2)
4. 7y(3 - x2 + 2x) + (-2x + x2 - 3)

I do not understand these ones

Answer 1

I will do the first one for you, and then you try the others, using the same method.

10x^2 + 2x - 5xy - y = ?

Factor out 2x from the first 2 terms, factor out -y from the last 2 terms, and get

2x(5x + 1) - y(5x + 1)

Now factor out 5x + 1 and get

(5x + 1)(2x - y)

It is now fully factored. Try the others.