Question

Giúp mk

Answer 1

Theo bài ra ta có:

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

Đặt \(\frac{a}{c}=\frac{b}{d}=k\)

\(\Rightarrow a=ck;b=dk\)

\\(\frac{a-c}{a}=\frac{ck-c}{ck}=\frac{c\cdot\left(k-1\right)}{ck}=\frac{k-1}{k}\) (1)

\(\frac{b-d}{b}=\frac{dk-d}{dk}=\frac{d\cdot\left(k-1\right)}{dk}=\frac{k-1}{k}\) (2)

Từ |(1) và (2)

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

Answer 2

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ab =cd ⇒ca =db ⇒1−ca =1−db ⇒a−ca =b−db