这三题怎么做?要有过程
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15、
原式===> 10/(x+3)(x-2)-2/(x-2)=1
===> 10-2(x+3)=(x+3)(x-2)
===> 10=(x+3)(x-2)+2(x+3)
===> 10=(x+3)(x-2+2)
===> 10=(x+3)x
===> x²+3x-10=0
===> (x-2)(x+5)=0
===> x=2(舍去),x=-5
16、
原式===> (x-2)(x+1)+(x+3)(x-1)+2=x²-1
===> x²-x-2+x²+2x-3+2=x²-1
===> x²+x-2=0
===> (x-1)(x+2)=0
===> x=1(舍去),x=-2
17、
原式===> [1+1/(x-5)]-[1+1/(x-6)]=[1+1/(x-8)]-[1+1/(x-9)]
===> 1/(x-5)-1/(x-6)=1/(x-8)-1/(x-9)
===> [(x-6)-(x-5)]/(x-5)(x-6)=[(x-9)-(x-8)]/(x-8)(x-9)
===> -1/(x-5)(x-6)=-1/(x-8)(x-9)
===> (x-5)(x-6)=(x-8)(x-9)
===> x²-11x+30=x²-17x+72
===> 6x=42
===> x=7
原式===> 10/(x+3)(x-2)-2/(x-2)=1
===> 10-2(x+3)=(x+3)(x-2)
===> 10=(x+3)(x-2)+2(x+3)
===> 10=(x+3)(x-2+2)
===> 10=(x+3)x
===> x²+3x-10=0
===> (x-2)(x+5)=0
===> x=2(舍去),x=-5
16、
原式===> (x-2)(x+1)+(x+3)(x-1)+2=x²-1
===> x²-x-2+x²+2x-3+2=x²-1
===> x²+x-2=0
===> (x-1)(x+2)=0
===> x=1(舍去),x=-2
17、
原式===> [1+1/(x-5)]-[1+1/(x-6)]=[1+1/(x-8)]-[1+1/(x-9)]
===> 1/(x-5)-1/(x-6)=1/(x-8)-1/(x-9)
===> [(x-6)-(x-5)]/(x-5)(x-6)=[(x-9)-(x-8)]/(x-8)(x-9)
===> -1/(x-5)(x-6)=-1/(x-8)(x-9)
===> (x-5)(x-6)=(x-8)(x-9)
===> x²-11x+30=x²-17x+72
===> 6x=42
===> x=7
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