(15-7xy)(-15-7xy)=(______)2-(______)2=______.
题型:填空题难度:简单来源:不详
(15-7xy)(-15-7xy)=(______)2-(______)2=______. |
答案
(15-7xy)(-15-7xy)=(7xy)2-(15)2=49x2y2-225. |
举一反三
(x+y)(x-y)(______)=x4-2x2y2+y4,(x+y)2=(x-y)2+______. |
用简便方法计算: (1)1982; (2)10.5×9.5; (3)2.39×91+156×2.39-2.39×47. |
利用乘法公式计算: (1)(2x-3y)2-(y+3x)(3x-y); (2)(x+y)(x2+y2)(x-y)(x4+y4); (3)(a-2b+3)(a+2b-3); (4)[(x-y)2+(x+y)2](x2-y2); (5)(m-n-3)2. |
利用乘法公式计算正确的是( )A.(2x-3)2=4x2+12x-9 | B.(4x+1)2=16x2+8x+1 | C.(a+b)(a+b)=a2+b2 | D.(2m+3)(2m-3)=4m2-3 |
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