计算:
(1)(2x+1)(-2x+1)
(2)(2a-b2)2
(3)(3x+1)2(3x-1)2
(4)(x+1)(x2+1)(x4+1)(x-1)
网友回答
解:(1)(2x+1)(-2x+1),
=12-(2x)2,
=1-4x2;
(2)(2a-b2)2,
=(2a)2-2×2a×b2+,
=4a2-2ab2+;
(3)(3x+1)2(3x-1)2,
=[(3x+1)(3x-1)]2,
=(9x2-1)2,
=81x4-18x2+1;
(4)(x+1)(x2+1)(x4+1)(x-1),
=(x+1)(x-1)(x2+1)(x4+1),
=(x2-1)(x2+1)(x4+1),
=(x4-1)(x4+1),
=x8-1.
解析分析:(1)根据平方差公式,找准a、b对应的数,再解答;
(2)根据完全平方公式,计算;
(3)和(4)可根据平方差公式,计算解答.
点评:本题考查了平方差公式和完全平方公式,熟练掌握这些公式是解题的关键.公式:(a+b)(a-b)=a2-b2,(a±b)2=a2±2ab+b2.