Question

化简与求值:(a+b)(a-b)+(a+b)2-a(2a+b),其中a=三分之二,b=负一又二分之一

Answer 1

(a+b)(a-b)+(a+b)^2-a(2a+b)

=a^2-b^2+a^2+2ab+b^2-4a-2b

=2a^2+2ab-4a-2b

=2x(2/3)^2-2x2/3x3/2-4x2/3+2x3/2

=8/9-2-8/3+3

=8/9-8/3+1

=8/9-24/9+1

=-7/9