Question

Cho \(\frac{a}{b}\)=\(\frac{c}{d}\)

CMR: \(\frac{7a-4b}{3a+5b}\)=\(\frac{7c-4d}{3c+5d}\)

Answer 1

chiu

tk nhe@@@@@@@@@@

xin do

bye

Answer 2

Đặt \(\frac{a}{b}=\frac{c}{d}=k\Rightarrow\hept{\begin{cases}a=bk\\c=dk\end{cases}}\)

Ta có: \(\frac{7a-4b}{3a+5b}=\frac{7bk-4b}{3bk-5b}=\frac{b\left(7k-4\right)}{b\left(3k-5\right)}=\frac{7k-4}{3k-5}\)(1)

\(\frac{7c-4d}{3c+5d}=\frac{7dk-4d}{3dk+5d}=\frac{d\left(7k-4\right)}{d\left(3k+5\right)}=\frac{7k-4}{3k+5}\)(2)

Từ (1) và (2) suy ra \(\frac{7a-4b}{3a+5b}=\frac{7c-4d}{3c+5d}\)(đpcm)

Answer 3

bạn đức hải sai r 3bk+5 chứ