先化简,再求值.已知:x+y=3,x-y=1,求2(x+y)^2-3(x-y)^2+[2(x+y)^3*(x-y)^2]^2÷[(x+y)^4*(x-y)^4]的值
先化简,再求值.已知:x+y=3,x-y=1,求2(x+y)^2-3(x-y)^2+[2(x+y)^3*(x-y)^2]^2÷[(x+y)^4*(x-y)^4]的值...
先化简,再求值.已知:x+y=3,x-y=1,求2(x+y)^2-3(x-y)^2+[2(x+y)^3*(x-y)^2]^2÷[(x+y)^4*(x-y)^4]的值
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2(x+y)^2-3(x-y)^2+[2(x+y)^3*(x-y)^2]^2÷[(x+y)^4*(x-y)^4]
=2(x+y)²-3(x-y)²+4(x+y)²
=6(x+y)²-3(x-y)²
∵x+y=3,x-y=1
∴原式
=6×3²-3×1²
=54-3
=51
=2(x+y)²-3(x-y)²+4(x+y)²
=6(x+y)²-3(x-y)²
∵x+y=3,x-y=1
∴原式
=6×3²-3×1²
=54-3
=51
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