当1/x=14-x时,求{[(x^2-5)/(x-1)+1]*[(x^3-1)/(x^2-2x)]}/(x+3)的值
问题描述:
当1/x=14-x时,求{[(x^2-5)/(x-1)+1]*[(x^3-1)/(x^2-2x)]}/(x+3)的值
答
1/x=14-x
x+1/x=14
原式=[(x²-5+x-1)/(x-1)][(x-1)(x²+x+1)/x(x-2)]/(x+3)
=[(x+3)(x-2)/(x-1)][(x-1)(x²+x+1)/x(x-2)]/(x+3)
=(x²+x+1)/x
=x+1+1/x
=14+1
=15