①化简：[x(x^3y^2)^2-2(x^2y)^3]×(-xy^2)^3②先化简再求值：[x^2y^2(x+y)^2-xy^2(x^3+xy^2)]/(1/2x^2y),其中x=1/2,y=1③先化简再求值：[(a+2b)(a-2b)-(2a-b)^2+(3a-b)(3a-5b)]/2a,其中a=-1,b=2④先化简再求值：(a+b)(a-b)+2a^2,其
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①化简：[x(x^3y^2)^2-2(x^2y)^3]×(-xy^2)^3②先化简再求值：[x^2y^2(x+y)^2-xy^2(x^3+xy^2)]/(1/2x^2y),其中x=1/2,y=1③先化简再求值：[(a+2b)(a-2b)-(2a-b)^2+(3a-b)(3a-5b)]/2a,其中a=-1,b=2④先化简再求值：(a+b)(a-b)+2a^2,其
①化简：[x(x^3y^2)^2-2(x^2y)^3]×(-xy^2)^3
②先化简再求值：[x^2y^2(x+y)^2-xy^2(x^3+xy^2)]/(1/2x^2y),其中x=1/2,y=1
③先化简再求值：[(a+2b)(a-2b)-(2a-b)^2+(3a-b)(3a-5b)]/2a,其中a=-1,b=2
④先化简再求值：(a+b)(a-b)+2a^2,其中a=1,b=根号2
①化简：[x(x^3y^2)^2-2(x^2y)^3]×(-xy^2)^3②先化简再求值：[x^2y^2(x+y)^2-xy^2(x^3+xy^2)]/(1/2x^2y),其中x=1/2,y=1③先化简再求值：[(a+2b)(a-2b)-(2a-b)^2+(3a-b)(3a-5b)]/2a,其中a=-1,b=2④先化简再求值：(a+b)(a-b)+2a^2,其
1. [x(x3y2)2-2(x2y)3]×(-xy2)3
=[x(x6y4)-2(x6y3)]×(-x3y6)
=(x7y4-2x6y3)×(-x3y6)
=-x10y10+2x9y9
= x9y9(2-xy)
2. [x2y2(x+y)2-xy2(x3+xy2)]/(1/2x2y)
=[x2y2(x2+2xy+y2)-x4y2- x2y4] /(1/2x2y)
=( x4y2+2 x3y3+ x2y4- x4y2- x2y4) /(1/2x2y)
=2 x3y3/(1/2x2y)
=4xy2
∵x=1/2,y=1;∴4xy2=4×1/2×12=2
3. [(a+2b)(a-2b)-(2a-b)2+(3a-b)(3a-5b)]/2a
=[a2-2ab+2ab-4b2-(4a2-4ab+b2)+(9a2-15ab-3ab+5b2)]/2a
=( a2-4b2-4a2+4ab-b2+9a2-18ab+5b2)/2a
=(6a2-14ab)/2a
=3a-7b
∵a=-1,b=2;∴3a-7b=3×(-1)-7×2=-17
4. (a+b)(a-b)+2a2
=a2-b2+2a2
=3a2-b2
∵a=1,b=√2;∴3a2-b2=3-2=1