计算; (1)(b-1)(1+b)(b²-1): (2)(1/3a+3b)²-(1/3-3b)²; 2.求值:[(x+2y-3/2)(x-2y+3/2)
计算;(1)(b-1)(1+b)(b²-1):(2)(1/3a+3b)²-(1/3-3b)²;2.求值:[(x+2y-3/2)(x-2y+3...
计算;
(1)(b-1)(1+b)(b²-1): (2)(1/3a+3b)²-(1/3-3b)²;
2.求值:[(x+2y-3/2)(x-2y+3/2)+2y(2y-3)+(2/3¯²)](-3x)¯¹,其中x=-1,y=2007/2006. 展开
(1)(b-1)(1+b)(b²-1): (2)(1/3a+3b)²-(1/3-3b)²;
2.求值:[(x+2y-3/2)(x-2y+3/2)+2y(2y-3)+(2/3¯²)](-3x)¯¹,其中x=-1,y=2007/2006. 展开
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计算;(1)(b-1)(1+b)(b²-1):
=(b²-1)(b²-1)
=b^4-2b²+1
(2)题目应是 (1/3a+3b)²-(1/3a-3b)²;
=(1/3a+3b +1/3a-3b)(1/3a+3b-1/3a+3b)
=(2/3a)(6b)
=4ab
2.求值:[(x+2y-3/2)(x-2y+3/2)+2y(2y-3)+(2/3¯²)](-3x)¯¹,其中x=-1,y=2007/2006.
=[(x^2-(2y-3/2)^2+2y(2y-3)+9/4)](-1/3x)
=[x^2-4y^2+6y-9/4+4y^2-6y+9/4](-1/3x)
=(x^2)(-1/3x)
=-x/3
=-(-1)/3
=1/3
=(b²-1)(b²-1)
=b^4-2b²+1
(2)题目应是 (1/3a+3b)²-(1/3a-3b)²;
=(1/3a+3b +1/3a-3b)(1/3a+3b-1/3a+3b)
=(2/3a)(6b)
=4ab
2.求值:[(x+2y-3/2)(x-2y+3/2)+2y(2y-3)+(2/3¯²)](-3x)¯¹,其中x=-1,y=2007/2006.
=[(x^2-(2y-3/2)^2+2y(2y-3)+9/4)](-1/3x)
=[x^2-4y^2+6y-9/4+4y^2-6y+9/4](-1/3x)
=(x^2)(-1/3x)
=-x/3
=-(-1)/3
=1/3
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