(1)计算:3a(5a-2b)(2)计算:(y+2)(y-2)-(y-1)(y+5)(3)计算:[(2m+n)2-n(4m+n)]÷(-2m)(4)因式分解:6
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(1)计算:3a(5a-2b) (2)计算:(y+2)(y-2)-(y-1)(y+5) (3)计算:[(2m+n)2-n(4m+n)]÷(-2m) (4)因式分解:6xy2-9x2y-y3 |
答案
(1)3a(5a-2b), =15a2-6ab;
(2)(y+2)(y-2)-(y-1)(y+5), =y2-4-y2-4y+5, =1-4y;
(3)[(2m+n)2-n(4m+n)]÷(-2m), =(4m2+4mn+n2-4mn-n2)÷(-2m), =4m2÷(-2m), =-2m;
(4)6xy2-9x2y-y3, =-y(9x2-6xy+y2), =-y(3x-y)2. |
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