9(x-5y)²-49(x+5y)²
来源:学生作业帮助网 编辑:作业帮 时间:2024/09/08 15:26:33
![9(x-5y)²-49(x+5y)²](/uploads/image/z/3780050-50-0.jpg?t=9%28x-5y%29%26%23178%3B-49%28x%2B5y%29%26%23178%3B)
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9(x-5y)²-49(x+5y)²
9(x-5y)²-49(x+5y)²
9(x-5y)²-49(x+5y)²
9(x-5y)²-49(x+5y)²
=[3(x-5y)]²-[7(x+5y)]²
=[3(x-5y)+7(x+5y)][3(x-5y)-7(x+5y)]
=(3x-15y+7x+35y)(3x-15y-7x-35y)
=(10x-20y)(-4x-50y)
=-20(x-2y)(2x+25y)
9(x^2-10xy+25y^2)-49(x^2+10xy+25y^2)
=18x^2-90xy+225y^2-49x^2-490xy-1225y^2
=-31x^2-580xy-1000y^2