m分之1-n分之1=3
兩邊乘以mn得
n-m=3mn
∴m-n=-3mn
m-2mn-n分之2m+3mn-2n
=[2(m-n)+3mn]/[(m-n)-2mn]
=(-6mn+3mn)/(-3mn-2mn)
=3/5a分之a+1×(a+1分之2a)²-[(a-1分之1)-(a+1分之1)]=(a+1)/a×4a²/(a+1)²-1/(a-1)+1/(a+1) =4a/(a+1)+1/(a+1)-1/(a-1) =(4a+1)/(a+1)-1/(a-1) =[(4a+1)(a-1)-(a+1)]/(a+1)(a-1)=(4a²-4a-2)/(a²-1)