1/(x+3)=4/5左右两边同时乘以 5(x+3)5=4(x+3)4x+12=54x=-7x=-7/4x=负四分之七
1/[x+3]=五分之四 交叉相乘4(x+3)=54x+12=54x=5-124x=-7x=-7/4
1/(x+3)=4/5 - 4/(4x+12)=4/5 - 4x+12=5 - x=-7/4
-7/4
X=负1又4分之3
1/[x+3]=4/5解:5=4x+124x=-7x=-7/4