Question

cho : \(\frac{a}{b}\)=\(\frac{c}{d}\). hãy chứng tỏ rằng ad=bc

Answer 1

\(\frac{a}{b}=\frac{c}{d}\Rightarrow\frac{ad}{bd}=\frac{bc}{bd}\Rightarrow ad=bc\)

Answer 2

\(\frac{a}{b}=\frac{c}{d}\Rightarrow a=\frac{bc}{d}\Rightarrow ad=bc\)

Answer 3

Ta có: \(\frac{a}{b}=\frac{ad}{bd};\frac{c}{d}=\frac{ac}{bd}\)

Vì \(\frac{ad}{bd};\frac{ac}{bd}\)cùng mẫu là bd 

Mà a=c => ac=bd

=>ĐPCM