Question

factor by grouping 21x+15-14xz^3-10yz^2

Answer 1

Factor out a common factor out of the first two terms.
Factor out a common factor out of the last two terms.
You must end up with the same expression inside both sets of parentheses.
Be careful when factoring the last two terms. Since they are both negative, you can factor out a negative quantity and make both terms inside the parentheses positive.