bài 3 tính tổng
A= $\frac{3}{17}$ +$\frac{-5}{13}$ +$\frac{-18}{35}$ +$\frac{14}{17}$+ $\frac{17}{-35}$ +$\frac{-8}{13}$
B= $\frac{4}{20}$ +$\frac{16}{42}$+ $\frac{6}{15}$+ $\frac{-3}{5}$+ $\frac{2}{21}$ +$\frac{-10}{21}$ +$\frac{3}{20}$
bài 3 tính tổng
A= $\frac{3}{17}$ +$\frac{-5}{13}$ +$\frac{-18}{35}$ +$\frac{14}{17}$+ $\frac{17}{-35}$ +$\frac{-8}{13}$
B= $\frac{4}{20}$ +$\frac{16}{42}$+ $\frac{6}{15}$+ $\frac{-3}{5}$+ $\frac{2}{21}$ +$\frac{-10}{21}$ +$\frac{3}{20}$
Đáp án:
Giải thích các bước giải:
`A=3/17 + (-5/13) + (-18/35) + 14/17 + (17/-35) + (-8/13)`
`A=(3/17 +14/17) – (5/13 + 8/13) – (18/35 + 17/35)`
`A= 17/17 – 13/13 – 35/35`
`A= 1-1-1`
`A=-1.`
`B = 4/20 + 16/42 + 6/15 + (-3/5) + 2/21 + (-10/21) + 3/20`
`B= 1/5 + 8/21 + 2/5 + (-3/5) + 2/21 + (-10/21) + 3/20`
`B= (1/5 + 2/5 – 3/5) + (8/21 + 2/21 – 10/21) + 3/20`
`B= 0/5 + 0/21 +3/20`
`B= 3/20.`
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