(2a+b)(3a+b)-(a+b)^2怎么解

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(2a+b)(3a+b)-(a+b)^2怎么解
(2a+b)(3a+b)-(a+b)^2怎么解

(2a+b)(3a+b)-(a+b)^2怎么解
(2a+b)(3a+b)-(a+b)^2
=(6a^2+2ab+3ab+b^2)-(a^2+2ab+b^2)
=6a^2+5ab+b^2-a^2-2ab-b^2
=5a^2+3ab

=6a^2+2ab+3ab+b^2-a^2-2ab-b^2
=5a^2+3ab
=a(5a+3b)

(3a+b)x(2a+b)-(a+b)的平方 =6a^2+3ab+2ab+b^2-a^2-b^2-2ab =5a^2+3ab =a(5a+3b) a=3,b=2 =63