\(\frac{a}{b}=\frac{c}{d}\Rightarrow\frac{a}{c}=\frac{b}{d}\)
Áp dụng TC DTSBN ta có :
\(\frac{a}{c}=\frac{b}{d}=\frac{a+b}{c+d}=\frac{a-b}{c-d}\Rightarrow\frac{a-b}{a+b}=\frac{c-d}{c+d}\) ( đpcm )
tu a/b=c/d=>a/c=b/d
áp dụng tính chất DTSBN TA CÓ
a/c=b/d=a-c/b-d=a+c/b+d từ a-c/b-d => a-b/a+b=c-d/c+d
ta co a/b=c/d=>a/d=b/c
ad t/c dTSBN TA CO
A/C=B/D=A-C/B-D=A+C/B+D
=>A-B/A+B=C-D/C+D
TA CÓ
A/B=C/D=A/D=B/C
AD TC DTSBN TA CÓ
A/C=B/D=>A-C=B-D=A+C/B+D
=>A-B/A+B=C-D/C+D
ta co A/B=C/D=A/D=B/C
AD T/C DTSBN TA CO
A/C=B/D=>A-C/B-D=A+C/B+D
=>A-B/A+B=C-D/C+Đ