\(\frac{a}{b}=\frac{c}{d}\Rightarrow\frac{b}{a}=\frac{d}{c}\Rightarrow\frac{b}{a}+1=\frac{d}{c}+1\)=> \(\frac{b+a}{a}=\frac{d+c}{c}\)=> \(\frac{a}{a+b}=\frac{c}{c+d}\)
a/b=c/d
=>ad=bc
=>ad+1=bc+1
=>a/b+1=c/d+1
=>a+b/b=c+d/c
=>a/a+b=c/c+d
a/b=c/d
suy ra ad=bd
suy ra ad+ac=bc+ac
suy ra a(d+c)=c(b+a)
suy ra a/a+b=c/b+a
(a+b-c)-(b-c+d) đơn giản biểu thức nhé làm đúng mik k
vì a/b=c/d=>ad=bc=>ac+ad=bc+ac=>a(d+c)=c(b+a)=>a/(b+a)=c/(c+d)
vậy .....