how do i simplify a(a - 3) ?

Question

how do i simplify the problem above? i have more problems to simplify such as 7(3^2 + 1) or -3d^2(d - 4). i do not understand how to do these, despite the book explanation 

Answer 1

You use the distributive law (or property).

Read the book carefully, ask questions of teacher, parent, or a good student; use Google to find explanatory videos for the Distributive Property in mathematics.

 

Basically, the factor outside the parentheses multiplies everything inside the parentheses; a(a-2) = a times a minus 2 times a. Parentheses are then discarded.