vào phần này nhé
https://dinhnghia.vn/tinh-chat-cua-day-ti-so-bang-nhau.html
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{a+c}{b+d}=\dfrac{a-c}{b-d}\)
\(\dfrac{a}{b}\)= \(\dfrac{c}{d}\)= \(\dfrac{a\pm c}{b\pm d}\)
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{a+c}{b+d}=\dfrac{a-c}{b-c}\)
Hoặc
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{e}{h}=\dfrac{a+c-e}{b+d-h}=\dfrac{a-c+e}{b-d+h}=\dfrac{a+c+e}{b+d+h}=\dfrac{a-c-e}{b-d-h}\)