Answers:
Step 1 is distributive property
Step 2 is distributive property (again)
Step 3 is commutative property
===============================================
Explanation:
The distributive property is the idea of multiplying the outer value by each inside value in the parenthesis. In general, the rule is a*(b+c) = a*b+a*c. We have the outer term 'a' multiplied by each inner term b and c. Then we add the products. The distributive property is used twice to multiply the two binomials. Your teacher and/or book may refer to it as the FOIL rule. FOIL stands for "first, outer, inner, last" which is a handy way to remember the order in how to multiply binomials.
The commutative property is the idea of adding or multiplying two values in any order we want. In this case, we're focusing on adding. This allows us to swap the terms to go from -5y^2+9x^2 to 9x^2+(-5y^2) = 9x^2-5y^2
