问题描述:
已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值.已知X+1/X=3,求x平方+1/x平方的值.(两题的转化的过程?
问题描述:
已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值.已知X+1/X=3,求x平方+1/x平方的值.(两题的转化的过程?
1/x-1/y=5 (y-x)/xy=5 (x-y)/xy=-5 (3x+5xy-3y)/(x-3xy-y) =[3(x-y)+5xy]/[(x-y)-3xy] =[3(x-y)/xy+5]/[(x-y)/xy-3] =[3×(-5)+5]/(-5-3) =(-10)/(-8) =5/4 x+1/x=3 (x+1/x)²=9 x²+2+1/x²=9 x²+1/x²=7