Question

Ta có: a/b = c/d

CMR: 3a - 4b/b = 3c - 4d/d

4 cách

Answer 1

C₁: Ta có: \(\dfrac{a}{b}=\dfrac{c}{d}\Rightarrow a=bk;c=dk\)

\(\Rightarrow\dfrac{3a-4b}{b}=\dfrac{bk-4b}{b}=\dfrac{b\left(k-4\right)}{b}=k-4\left(1\right)\)

\(\Rightarrow\dfrac{3c-4d}{d}=\dfrac{dk-4d}{d}=\dfrac{d\left(k-4\right)}{d}=k-4\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\dfrac{3a-4b}{b}=\dfrac{3c-4d}{d}\)