Question

tim x va y: 

\(\frac{x+3}{y+5}=\frac{x+5}{y+7}\)

giải hẳn ra

Answer 1

theo t/c dãy tỉ số = nhau;

\(\frac{x+3}{y+5}=\frac{x+5}{y+7}=\frac{\left(x+5\right)-\left(x+3\right)}{\left(y+7\right)-\left(y+5\right)}=\frac{x+5-x-3}{y+7-y-5}=\frac{2}{2}=1\)

=>x+3=y+5

=>x-y=5-3

=>x-y=2

vậy x-y=2