1.（2x+3y)^2-(2x+y)(2x-y)=(2x+y)（2x+3y-2x+y）=4y(2x+y)
代入原式=7/3.
2..[（x-y)^2+(x-y)(x+y)]/x=[（x-y)(x-y+x+y)]/x=2(x-y)
代入=-3.
3.4x(y-x)+(2x+y)(2x-y)=4xy-4x^2+4x^2-y^2=4xy-y^2=-4-4=-8
4.2(x+5)(x-4)-3(x-6)(x+1)=2(x^2+x-20)-3(x^2-5x-6)=-x^2+17x-22
代入=8
5.因为根号5＜b＜根号10,且b为整数所以b=3.
(2a-b)(b+2a)+2b(a+b)-3a^2b/b=4a^2-b^2+2ab+2b^2-3a^2=a^2+b^2+2ab=(a+b)^2=49/4