化简求值1.3(m+1)^2-5(m+1)(m-1)+2m(m-1),其中m=5

问题描述:

化简求值1.3(m+1)^2-5(m+1)(m-1)+2m(m-1),其中m=5
要写出过程,一定要仔细哦!准确!……
化简求值
1.3(m+1)^2-5(m+1)(m-1)+2m(m-1),其中m=5
2.2(x+4)^2-(-x-5)^2-(x+3)(x-3),其中x=-2
3.((x+y)分之1-(x-y)分之1 )÷(x^2-2xy+y^2)分之2x
1.3(m+1)^2-5(m+1)(m-1)+2m(m-1),其中m=5
2.2(x+4)^2-(-x-5)^2-(x+3)(x-3),其中x=-2
3.((x+y)分之1-(x-y)分之1 )÷(x^2-2xy+y^2)分之2x 其中x=2 y=-1
1个回答 分类:数学 2014-12-14

问题解答:

我来补答
1.3(m+1)^2-5(m+1)(m-1)+2m(m-1)
=3m^2+6m+3-5m^2+5+2m^2-2m
=4m+8
=2(m+2)
=2(5+2)
=14
2.2(x+4)^2-(-x-5)^2-(x+3)(x-3)
=2x^2+16x+32-x^2-10x-25-x^2+9
=6x+16
=6*(-2)+16
=4
3.[1/(x+y)-1/(x-y)]÷2x/(x^2-2xy+y^2)
={[(x-y)-(x+y)]/(x+y)(x-y)}÷2x/(x-y)^2
=[-2y/(x-y)(x+y)]÷2x/(x-y)^2
=y(y-x)/x(x+y)
 
 
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