81x的4次方-36a平方x平方 a的4次方=?
81x^4-36a^2x^2 a^4=[(9x²)²-2(9x²)a² (a²)²]-18a²x²=(9x²-a²)²-(3√2ax)²=(9x² 3√2ax-a²)(9x²-3√2ax-a²)=[6x (√2-√6)a][6x (√2 √6)a][6x-(√2-√6)a][6x-(√2 √6)a]/1296
纠正:最后结果的分母是16
答:x^4+y^4=25,x^2y-xy^2=-6, x^4-y^4+3xy^2-x^2y-2xy^2+2y^4 =x^4+y^4+xy^2-x^2y =x^4+y...详情>>
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