解答数学,拜托
2015-01-23
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原式
= (a - b/2)[(a^2 + ab + b^2/4) - (a^2-ab+b^2/4)](a^2+ab/2+b^2) - 2b(a^4 - 1)
= (a - b/2)(2ab)(a^2+ab/2+b^2) - 2b(a^4 - 1)
= (2a^4b + a^3b^2 + 2a^2b^3 - a^3b^2 - a^2b^3/2 + ab^4) - 2a^4b + 2b
= 3a^2b^3/2 + ab^4 + 2b
当a = 2,b=-1时
原式
= 3×2^2×(-1)^3/2 + 2×(-1)^4 + 2×(-1)
= -6 + 2 - 2
= -6
答题不易,请及时采纳,谢谢!
= (a - b/2)[(a^2 + ab + b^2/4) - (a^2-ab+b^2/4)](a^2+ab/2+b^2) - 2b(a^4 - 1)
= (a - b/2)(2ab)(a^2+ab/2+b^2) - 2b(a^4 - 1)
= (2a^4b + a^3b^2 + 2a^2b^3 - a^3b^2 - a^2b^3/2 + ab^4) - 2a^4b + 2b
= 3a^2b^3/2 + ab^4 + 2b
当a = 2,b=-1时
原式
= 3×2^2×(-1)^3/2 + 2×(-1)^4 + 2×(-1)
= -6 + 2 - 2
= -6
答题不易,请及时采纳,谢谢!
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