计算:(1)(2x+y-3z)2;(2)(x-y+4)(x+y+4).
题型:解答题难度:一般来源:不详
计算: (1)(2x+y-3z)2; (2)(x-y+4)(x+y+4). |
答案
(1)(2x+y-3z)2 =[(2x+y)-3z]2 =(2x+y)2-2•(2x+y)•3z+9z2 =4x2+4xy+y2-12xz-6yz+9z2;
(2)(x-y+4)(x+y+4) =[(x+4)-y][(x+4)+y] =(x+4)2-y2 =x2+8x+16-y2. |
举一反三
计算(x-3y)(x+3y)的结果是( )A.x2-3y2 | B.x2-6y2 | C.x2-9y2 | D.2x2-6y2 |
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499×501可表示为( )A.5002+12 | B.5002-12 | C.5002-4992 | D.5002+4992 |
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填空:x2+______+=______2;______(-2x+3y)=9y2-4x2 |
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