(3a -b)(a+b)+(b-3a)(b+3a)

Question

(3a -b)(a+b)+(b-3a)(b+3a)

Answer 1

(3а-b)(a+b)+(b-3a)(b+3a)=3a2+3ab-ab-b2+b2+3ab-3ab-3a2=3ab-ab=2ab
вроде бы так))

Answer 2

(3a -b)(a+b)+(b-3a)(b+3a)=3a²+3ab-ab-b²+b²+3ab-3ab-9a²=-6a²+2ab=-2a(3a-2b)