giúp mik mik tick cho
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a, Áp dụng t/c dtsbn:
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{a+c}{b+d}\)
b, Áp dụng t/c dtsbn:
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{2021a}{2021b}=\dfrac{2021a-c}{2021b-d}\)
c, Ta có \(\dfrac{a}{b}=\dfrac{c}{d}\Rightarrow\left(\dfrac{a}{b}\right)^2=\left(\dfrac{c}{d}\right)^2\)
Áp dụng t/c dtsbn:
\(\left(\dfrac{a}{b}\right)^2=\left(\dfrac{c}{d}\right)^2=\dfrac{a^2}{b^2}=\dfrac{c^2}{d^2}=\dfrac{a^2+c^2}{b^2+d^2}\)
khongcamxuc_123 đó nha bn bn phải giữ lời hứa đấy nha
~~~~ hok tốt ~~~~!!!!
a) \(\dfrac{-7}{5}\) . \(\dfrac{4}{23}\) + \(\dfrac{4}{23}\) . \(\dfrac{2}{5}\)
= \(\dfrac{4}{23}\) . ( \(\dfrac{-7}{5}\) + \(\dfrac{2}{5}\) )
= \(\dfrac{4}{23}\) . -1
= \(\dfrac{-4}{23}\)
b) \(\dfrac{-6}{7}\) . \(\dfrac{3}{5}\) +\(\dfrac{-6}{7}\) .\(\dfrac{2}{5}\) - \(1\dfrac{1}{3}\)
= \(\dfrac{-6}{7}\) . \(\dfrac{3}{5}\) +\(\dfrac{-6}{7}\) .\(\dfrac{2}{5}\) - \(\dfrac{4}{3}\)
= \(\dfrac{-6}{7}\) . (\(\dfrac{3}{5}\) + \(\dfrac{2}{5}\) ) - \(\dfrac{4}{3}\)
= \(\dfrac{-6}{7}\) . 1 - \(\dfrac{4}{3}\)
= \(\dfrac{-6}{7}\) - \(\dfrac{4}{3}\)
= \(\dfrac{-18}{21}\) - \(\dfrac{28}{21}\)
= \(\dfrac{-18}{21}\) + \(\dfrac{-28}{21}\)
= \(\dfrac{-46}{21}\)
kich j zậy hả?
kich cho em đi