化简求值:{(xy+2)(xy-2)
来源:百度知道 编辑:UC知道 时间:2024/05/31 22:08:12
1.{(xy+2)(xy-2)-2x^2 y^2+4 }/(xy),其中x=10 y=-1/25
2.(2a+b+1)(2a+b-1)
2.(2a+b+1)(2a+b-1)
1.{(xy+2)(xy-2)-2x^2 y^2+4 }/(xy),其中x=10 y=-1/25
=(x^2y^2-4-2x^2y^2+4)/xy
=(-x^2y^2)/xy
=-xy
=-10*(-1/25)
=2/5
2.(2a+b+1)(2a+b-1)
=(2a+b)^2-1
=4a^2+4ab+b^2-1
1.{(xy+2)(xy-2)-2x^2 y^2+4 }/(xy),
=(x^2y^2-4-2x^2 y^2+4) /(xy)= -xy=2/5
2.(2a+b+1)(2a+b-1)=(2a+b)^2-1
1.{(xy+2)(xy-2)-2x^2 y^2+4 }/(xy)
={x^2y^2-4-2x^2 y^2+4}/(xy)
=(-x^2 y^2)/(xy)
=-xy
当x=10 y=-1/25 时
-xy=2/5
2. (2a+b+1)(2a+b-1)
=[(2a+b)+1][(2a+b)-1]
=(2a+b)^2-1
=4a^2+b^2+4ab-1
1.(x^2y^2-4-2x^2y^2+4)/xy
==(-x^2y^2)/xy
=-xy
=2/5
2.(2a+b)^2-1
=4a^2+4ab+b^2-1
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