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1.计算:(2x-5y)²(5x+2y)² 2.因式分解:(x²-2x)²-11

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1.计算:(2x-5y)²(5x+2y)² 2.因式分解:(x²-2x)²-11(x²-2x)-24
.(2X-5Y)²(5X+2Y)².
=[ (2X-5Y)(5X+2Y)]²
=(10X² - 21XY + 10Y²)²
=100x^4 -420yx^3+641X²Y²-420xy^3+100y^4
(x^2+2x)^2-11(x^2+2x)+24
令x^2+2x=t
原式=t^2-11t+24
=t^2-(8+3)t+8*3
=(t-3)(t-8)
=(x^2+2x-3)(x^2+2x-8)
=[x^2+(3+(-1))x+3*(-1)][x^2+(4+(-2))x+4*(-2)]
=(x-1)(x+3)(x-2)(x+4)