Tinh
5/11 . 5/7 + 2/11 - 14/11 . 5/7
5/7×5/11+5/7×2/11-5/7×14/11
\(\dfrac{5}{7}\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}\times-\dfrac{7}{11}=\dfrac{-5}{11}\)
= 5/7 x ( 5/11 + 2/11 - 14/11 )
= 5/7 x -7/11
= -5/11
5/7 x ( 5/11 + 2/11 - 14/11) = 5/7 x -7/11 = -5/11
5/7×5/11+5/7×2/11-5/7×14/11
5/7×5/11+5/7×2/11-5/7×14/11
= 5/7 x ( 5/11 + 2/11 - 14/11 )
= 5/7 x -7/11
= -35/77
thu gọn các biểu thức sau
a)C=3^14+3^15+3^16+3^17+...+3^n
b)D=3^11+3^14+3^17+3^20+...+3^2021
c) E= -5^2-5^4-5^6-5^8-...-5^1000
d)F=-5^21-5^23-5^25-5^27-...-5^2019
e)M=7^2-7^4+7^6-7^8+...-7^1000
d)N=-12+11^2+11^3-11^4-11^5+...+11^498+11^499
b: \(27D=3^{14}+3^{17}+...+3^{2024}\)
\(\Leftrightarrow26D=3^{2024}-3^{11}\)
hay \(D=\dfrac{3^{2024}-3^{11}}{26}\)
c: \(25E=-5^4-5^6-...-5^{1002}\)
\(\Leftrightarrow24E=-5^{1002}+5^2\)
hay \(E=\dfrac{-5^{1002}+5^2}{24}\)
5/7. -5/7+ 5/7.-2/11-5/7.-14/11
\(\frac{5}{7}.\frac{-5}{7}+\frac{5}{7}.\frac{-2}{11}-\frac{5}{7}.\frac{-14}{11}\)
\(=\frac{5}{7}.\left(\frac{-5}{7}+\frac{-2}{11}-\frac{-14}{11}\right)\)
\(=\frac{5}{7}.\frac{29}{77}\)
\(=\frac{145}{539}\)
5/7*12/11+9/7*2/11-5/7*14/11
\(\frac{5}{7}.\frac{12}{11}+\frac{9}{7}.\frac{2}{11}-\frac{5}{7}.\frac{14}{11}\)
\(=\frac{1}{7}.\frac{1}{11}.\left(5.12+9.2-5.14\right)\)
\(=\frac{1}{77}.\left(60+18-70\right)\)
\(=\frac{1}{77}.8=\frac{8}{77}\)
Thực hiện phép tính có thể
5/7×5/11+5/7×2/11-5/7×14/11
\(\dfrac{5}{7}\)x\(\dfrac{5 }{11}\)\(+\dfrac{5}{7}\)\(\text{x}\dfrac{2}{11}\)\(-\dfrac{5}{7}\)\(\text{x}\dfrac{14}{11}\)
`5/7xx5/11+5/7xx2/11-5/7xx14/11`
`=5/7xx(5/11+2/11-14/11)`
`=5/7xx(-7/11)`
`=-5/11`
\(\dfrac{5}{7}\times\dfrac{5}{11}+\dfrac{5}{7}\times\dfrac{2}{11}-\dfrac{5}{7}\times\dfrac{14}{11}\)
=\(\dfrac{5}{7}\times\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)\)
=\(\dfrac{5}{7}\)\(\times-\dfrac{7}{11}\)
=\(-\dfrac{5}{11}\)
Chúc bạn học tốt nhé
57×(511+211−1411)57×(511+211−1411)
=×−711×−711
=
tinh bang hai cach
(6/11+5/11) * 3/7
(6/7-4/7) : 2/5
3/5 * 7/9 - 3/5 *2/9
8/15 : 2/11 + 7/15 :2/11
a ,b
cách 1 : cộng 2 số trong ngặc rồi tính bình thường
cách 2 : nhân phân phối ra rồi tính nhân chia trước cộng trừ sau
c,d
cách 1 : tính bình thường, nhân chia trc cộng trừ sau
cách 2 : đặt nhân tử ( thừa số ) chung
Cách 1 : \((\frac{6}{11}+\frac{5}{11})\cdot\frac{3}{7}=1\cdot\frac{3}{7}=\frac{3}{7}\)
Cách 2 : \(\frac{6}{11}\cdot\frac{3}{7}+\frac{5}{11}\cdot\frac{3}{7}=\frac{18}{77}+\frac{15}{77}=\frac{33}{77}=\frac{3}{7}\)
Cách 1 dễ rồi nha
Cách 2 : \(\frac{6}{7}:\frac{2}{5}-\frac{4}{7}:\frac{2}{5}=\frac{15}{7}-\frac{10}{7}=\frac{5}{7}\)
Cách 1 tự làm
Cách 2 : \(\frac{3}{5}\cdot(\frac{7}{9}-\frac{2}{9})=\frac{3}{5}\cdot\frac{5}{9}=\frac{1}{3}\)
Cách 1 : ...
Cách 2 : \((\frac{8}{15}+\frac{7}{15}):\frac{2}{11}=1:\frac{2}{11}=\frac{2}{11\cdot1}=\frac{2}{11}\)
5/7 . 9/11 + -5/7 . -2/11 + 1/14
\(\dfrac{5}{7}\cdot\dfrac{9}{11}+\dfrac{-5}{7}\cdot\dfrac{-2}{11}+\dfrac{1}{14}=\dfrac{45}{77}+\dfrac{10}{77}+\dfrac{1}{14}=\dfrac{5}{7}+\dfrac{1}{14}=\dfrac{10}{14}+\dfrac{1}{14}=\dfrac{11}{14}\)
\(\dfrac{5}{7}.\dfrac{9}{11}-\dfrac{5}{7}.-\dfrac{2}{11}+\dfrac{1}{14}=\dfrac{5}{7}.\left(\dfrac{9}{11}+\dfrac{2}{11}\right)+\dfrac{1}{14}=\dfrac{5}{7}.1+\dfrac{1}{14}=\dfrac{10+1}{14}=\dfrac{11}{14}\)