5/(x+2)=5/2x
10x=5(x+2)
10x=5x+10
x=2
已知ab=1 且a不等于0求a/a+1加b/b+1的值
a/a+1加b/b+1
=[a(b+1)+b(a+1)]/[(a+1)(b+1)]
=(2ab+a+b)/(ab+1+a+b)
=(2×1+a+b)/(1+1+a+b)
=(2+a+b)/(2+a+b)
=1
2a+1/a²-1乘a²-2a+1/a²-a减1/a+1
=(2a+1)/(a+1)(a-1) × (a-1)²/a(a-1) - 1/(a+1)
=(2a+1)/a(a+1) - a/a(a+1)
=(2a+1-a)/a(a+1)
=1/a