Question

因式分解4(a-3)的平方-(a+3)的平方

（a+b）的平方-9a的平方

Answer 1

=[2(a-3)]²-(a+3)²
=[2(a-3)+(a+3)][2(a-3)-(a+3)]
=(3a-3)(a-9)
=3(a-1)(a-9)

(a+b)²-(3a)²
=(a+b+3a)(a+b-3a)
=(4a+b)(b-2a)

Answer 2

4(a-3)^2 -(a+3)^2 = (2a-6 +a+3) (2a-6 -a-3)= (3a-3)(a-9)=3(a-1)(a-9)

(a+b)^2 -9a^2 = (a+b +3a)(a+b -3a) = (4a+b)(b-2a)