更新时间2018-03-12 08:17:45
解:
18.
[(x+y)(x-y)/(x-y)∧2-x/(x-y)]×[x(x-y)/y∧2]
=[y/(x-y)]×[x(x-y)/y∧2]
=x/y
∵√(x+3)=0========>x=-3
∵y-√3=0============>y=√3
∴原式=x/y=-√3
19.
3x-5<2x=========>x<5
x-1≦4x+2=========>x≧-1
-1≦x<5
20.
1). 1<CD<9
2)
∠E=180-125=55
∠C=180-55*2=70度
[(x+y)(x-y)/(x-y)∧2-x/(x-y)]×[x(x-y)/y∧2]
=[y/(x-y)]×[x(x-y)/y∧2]
=x/y
∵√(x+3)=0========>x=-3
∵y-√3=0============>y=√3
∴原式=x/y=-√3
19.
3x-5<2x=========>x<5
x-1≦4x+2=========>x≧-1
-1≦x<5
20.
1). 1<CD<9
2)
∠E=180-125=55
∠C=180-55*2=70度
原式=((x²-y²)/(x²-2xy+y²)+x/(y-x))*(x²-xy)/y²
=((x+y)(x-y)/(x-y)²-x/(x-y))*(x²-xy)/y²
=(y/(x-y))*x(x-y)/y²=x/y
由(√x+3)+∣y-√3∣=0可知,x=-3,y=√3
所以原式=-3/√3=-√3
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