

Tính (Hợp lý nếu có thể):
C = 1,2 . 15/4 + 16/7 . -85/9 - 1,2 . 23/4 - 16/7 . -71/8
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Giải thích các bước giải:
Ta có:
$C=1.2\cdot \dfrac{15}4+\dfrac{16}7\cdot \dfrac{-85}9-1.2\cdot\dfrac{23}4-\dfrac{16}7\cdot \dfrac{-71}8$
$\to C=1.2\cdot (\dfrac{15}4-\dfrac{23}4)+\dfrac{16}7\cdot (\dfrac{-85}9+\dfrac{71}8)$
$\to C=\dfrac{6}{5}\left(\dfrac{15}{4}-\dfrac{23}{4}\right)+\dfrac{16}{7}\left(\dfrac{-85}{9}+\dfrac{71}{8}\right)$
$\to C=-\dfrac{12}{5}-\dfrac{82}{63}$
$\to C=\dfrac{-1166}{315}$
Hãy giúp mọi người biết câu trả lời này thế nào?

Đáp án ` + ` Hướng dẫn giải :
Ta có phép tính :
` C = 1.2 . 15/4 . 16/7 . -85/9 - 1.2 . 23/4 - 16/7 . - 71/8 `
` C = 1.2 . ( 15/4 - 23/4 ) + 16/7 . ( - 85/ 9 + 71/8 ) `
` C = 6/5 ( 15/4 - 23/4 ) + 16/7 ( - 85/9 + 71/8 ) `
` C = - 12/5 - 82/63`
` C = -1166/315 `
`PVZ2MK`
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