Question

[cún bông]

tính tổng

\(\frac{3}{7}+\frac{-2}{3}\)

tù đó có thể suy ra ngay kết quả các phép ccongj sau ko

\(\frac{9}{21}+\frac{-10}{15};\frac{24}{56}+\frac{-18}{27}\)

Answer 1

[Dương Lam Hàng]

Ta có: \(\frac{9}{21}=\frac{9:3}{21:3}=\frac{3}{7}\)

Và       \(\frac{-10}{15}=\frac{-10:5}{15:5}=-\frac{2}{3}\)

\(\Rightarrow\frac{9}{21}+\frac{-10}{15}=\frac{3}{7}+\frac{-2}{3}=\frac{9}{21}+\frac{-14}{21}=\frac{9+\left(-14\right)}{21}=\frac{-5}{21}\)

Tương tự: \(\frac{24}{56}=\frac{24:8}{56:8}=\frac{3}{7}\)

Và \(\frac{-18}{27}=\frac{-18:9}{27:9}=\frac{-2}{3}\)

\(\Rightarrow\frac{24}{56}+\frac{-18}{27}=\frac{3}{7}+\frac{-2}{3}=\frac{-5}{21}\)

Answer 2

[Aoi Ogata]

\(\frac{3}{7}+\frac{-2}{3}=\frac{9}{21}-\frac{14}{21}=\frac{-5}{21}\)

\(\frac{9}{21}+\frac{-10}{15}=\frac{3}{7}-\frac{2}{3}=\frac{-5}{21}\)

\(\frac{24}{56}+\frac{-18}{27}=\frac{3}{7}-\frac{2}{3}=\frac{-5}{21}\)