a) 5/8 . -6/13 + 5/8 . -7/13 + 13/8
b)2/5 . 15/4 – 2/5 . 10/9 + 1/2
Ét ô ét mấy chế ơi
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$\text{→ Giải đáp + Lời giải và giải thích chi tiết:}$$\text{a)}$$\text{→ Ta có :}$$\text{$\dfrac{5}{8}$ . $\dfrac{- 6}{13}$ + $\dfrac{5}{8}$ . $\dfrac{- 7}{13}$ + $\dfrac{13}{8}$}$$\text{= $\dfrac{5}{8}$ . ( $\dfrac{- 6 – 7}{13}$ ) + $\dfrac{13}{8}$}$$\text{= $\dfrac{- 5}{8}$ + $\dfrac{13}{8}$}$$\text{= $\dfrac{13 – 5}{8}$}$$\text{= 1}$$\text{b)}$$\text{→ Ta có :}$$\text{$\dfrac{2}{5}$ . $\dfrac{15}{4}$ – $\dfrac{2}{5}$ . $\dfrac{10}{9}$ + $\dfrac{1}{2}$}$$\text{= $\dfrac{2}{5}$ . ( $\dfrac{15}{4}$ – $\dfrac{10}{9}$ ) + $\dfrac{1}{2}$}$$\text{= $\dfrac{2}{5}$ . $\dfrac{15 . 9 – 10 . 4}{36}$ + $\dfrac{1}{2}$}$$\text{= $\dfrac{2}{5}$ . $\dfrac{135 – 40}{36}$ + $\dfrac{1}{2}$}$$\text{= $\dfrac{2 . 95}{5 . 36}$ + $\dfrac{1}{2}$}$$\text{= $\dfrac{190}{180}$ + $\dfrac{90}{180}$}$$\text{= $\dfrac{280}{180}$ = $\dfrac{14}{9}$}$5 sao nha