Toán 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 +1/90 19/07/2021 By Katherine 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 +1/90
1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90 =1/4+1/20+1/30+1/42+1/56+1/72+1/90 = 3/10+1/30+1/42+1/56+1/72+1/90 = 1/3+1/42+1/56+1/72+1/90 = 5/14+1/56+1/72+1/9 = 3/8+1/72+1/90 = 7/18+1/90 = 2/5 Hơi rối nhé bạn , chúc bạn học tốt Trả lời
$ A= \frac{1}{6}+\frac{1}{12}+\frac{1}{20}+…+\frac{1}{90}$ = $ \frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+…+\frac{1}{9.10}$ = $ \frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+…+\frac{1}{9}-\frac{1}{10}$ = $ \frac{1}{2}-\frac{1}{10}$ = $ \frac{2}{5}$ Trả lời
1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=1/4+1/20+1/30+1/42+1/56+1/72+1/90
= 3/10+1/30+1/42+1/56+1/72+1/90
= 1/3+1/42+1/56+1/72+1/90
= 5/14+1/56+1/72+1/9
= 3/8+1/72+1/90
= 7/18+1/90
= 2/5
Hơi rối nhé bạn , chúc bạn học tốt
$ A= \frac{1}{6}+\frac{1}{12}+\frac{1}{20}+…+\frac{1}{90}$
= $ \frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+…+\frac{1}{9.10}$
= $ \frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+…+\frac{1}{9}-\frac{1}{10}$
= $ \frac{1}{2}-\frac{1}{10}$
= $ \frac{2}{5}$