求初中数学300道计算题(主要是化简求值,解方程(2元1次,分式,1元1次)化简,计算)并附过程答案。
2个回答
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(1)简化分数(X ^ 2-1 / X ^ 2 +2 X +1) - (X +1 / X-1)
=(x +1)(X-1)/(X +1)^ 2 - (X +1)/(X-1)
=(x-1)/(X +1) - (X +1)/(X-1)
= [(x-1)^ 2 - (X +1)^ 2] /(X +1)(X-1)
=-4X /(X +1)(X-1)
(2)解方程(X-1 / X) - (x/x-1)= 5/2(过程)
(x-1)^ 2-X ^ 2 = 5/2x(X-1)
-2X +1 = 2.5倍^ 2-2.5倍
2.5倍^ 2-0.5X-1 = 0
5X ^ 2-X-2 = 0
X ^ 2-X / 5 = 2/5
(X-1/10)^ 2 = 2/5 +1 / 100 = 41/100
x-1/10 =(+ / - )41/10的平方根
X1 =(1 + 41的平方根)/ 10
X2的=(1 - 41的平方根)/ 10
检验X1,X2是方程的根。
=(x +1)(X-1)/(X +1)^ 2 - (X +1)/(X-1)
=(x-1)/(X +1) - (X +1)/(X-1)
= [(x-1)^ 2 - (X +1)^ 2] /(X +1)(X-1)
=-4X /(X +1)(X-1)
(2)解方程(X-1 / X) - (x/x-1)= 5/2(过程)
(x-1)^ 2-X ^ 2 = 5/2x(X-1)
-2X +1 = 2.5倍^ 2-2.5倍
2.5倍^ 2-0.5X-1 = 0
5X ^ 2-X-2 = 0
X ^ 2-X / 5 = 2/5
(X-1/10)^ 2 = 2/5 +1 / 100 = 41/100
x-1/10 =(+ / - )41/10的平方根
X1 =(1 + 41的平方根)/ 10
X2的=(1 - 41的平方根)/ 10
检验X1,X2是方程的根。
追问
不够用啊,求求你,再给加几道吧
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