Toán 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/90+1/110 21/11/2021 By Kylie 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/90+1/110
$\frac{1}{2}$+ $\frac{1}{6}$+ $\frac{1}{12}$+ $\frac{1}{20}$+ ….+$\frac{1}{90}$+ $\frac{1}{110}$ =>$\frac{1}{1×2}$+ $\frac{1}{2×3}$+ $\frac{1}{3×4}$+ $\frac{1}{4×5}$+ ….+$\frac{1}{9.10}$+ $\frac{1}{10×11}$ =>$\frac{1}{1}$-$\frac{1}{2}$+ $\frac{1}{2}$- $\frac{1}{3}$+ ….+$\frac{1}{10}$- $\frac{1}{11}$ =>1 – $\frac{1}{11}$ => $\frac{10}{11}$ Trả lời
Đáp án: `↓↓` Giải thích các bước giải: `1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110` `=1/(1×2)+1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)+1/(6×7)+1/(7×8)+1/(8×9)+1/(9×10)+1/(10×11)` `=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11` `=1/1-1/11` `=10/11` Trả lời
$\frac{1}{2}$+ $\frac{1}{6}$+ $\frac{1}{12}$+ $\frac{1}{20}$+ ….+$\frac{1}{90}$+ $\frac{1}{110}$
=>$\frac{1}{1×2}$+ $\frac{1}{2×3}$+ $\frac{1}{3×4}$+ $\frac{1}{4×5}$+ ….+$\frac{1}{9.10}$+ $\frac{1}{10×11}$
=>$\frac{1}{1}$-$\frac{1}{2}$+ $\frac{1}{2}$- $\frac{1}{3}$+ ….+$\frac{1}{10}$- $\frac{1}{11}$
=>1 – $\frac{1}{11}$
=> $\frac{10}{11}$
Đáp án:
`↓↓`
Giải thích các bước giải:
`1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110`
`=1/(1×2)+1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)+1/(6×7)+1/(7×8)+1/(8×9)+1/(9×10)+1/(10×11)`
`=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11`
`=1/1-1/11`
`=10/11`