![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{2}{3}\times\dfrac{3}{4}+\dfrac{3}{4}\times\dfrac{2}{5}=\dfrac{3}{4}\times\left(\dfrac{2}{3}+\dfrac{2}{5}\right)=\dfrac{3}{4}\times\dfrac{16}{15}=\dfrac{4}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
28 : x + 12 : x = 5
( 28 + 12 ) : x = 5
40 : x = 5
x = 40 : 5 = 8
Chúc bạn học tốt
\(\frac{28}{x}+\frac{12}{x}=5\)
\(\frac{28+12}{x}=\frac{5}{1}\)
\(=\frac{40}{x}=\frac{5}{1}\)
Ta lấy: \(\frac{40}{x}=\frac{40\div8}{x\div8}=\frac{5}{1}\)
Vậy: \(x=8\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{24\times14\times30}{28\times12\times60}\)
\(=\frac{24}{12}\times\frac{28}{14}\times\frac{60}{30}\)
\(=2\times2\times2\)
\(=8\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a)12\times11+28\times11+60\times11\)
\(=11\times\left(12+28+60\right)\)
\(=11\times100\)
\(=1100\)
\(b)11\times111\)
Ta thấy:
\(1+1=2\)
Thay \(2\) vào chữ số hàng chục và hàng trăm ta được:
\(11\times111=1221\)
Vậy \(11\times111=1221\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
`@` `\text {Ans}`
`\downarrow`
`A)`
`37 \times 46+37 \times 51+111`
`= 37 \times (46+51)+111`
`= 37 \times 97+111`
`= 3589 +111`
`= 3700`
`B)`
`35 \times 215-35 \times 210-175`
`= 35 \times (215-210)-175`
`= 35 \times 5-175`
`= 175-175=0`
`E)`
`76 \times 102-76 \times 2`
`= 76 \times (102-2)`
`= 76 \times 100`
`= 7600`
`C)`
`85 \times 94+85 \times 2 +170 \times 2`
`= 85 \times (94+2) + 170 \times 2`
`= 85 \times 96+170 \times 2`
`= 8160+340`
`= 8500`
`48 \times 56+28 \times 104`
`= 48 \times 28 \times 2+28 \times 104`
`= 28 \times (48 \times 2+104)`
`= 28 \times (96+104)`
`= 28 \times 200`
`= 5600`
`G)`
`206 \times 12-206-206`
`= 206 \times (12-1-1)`
`= 206 \times 10`
`= 2060`
a) 37 x 46 + 37 x 51 + 111
= 37 x ( 46 + 51 ) + 111
= 37 x 97 + 111
= 3589 + 111
= 3700
b) 35 x 215 - 35 x 210 - 175
= 35 x ( 215 - 210 ) - 175
= 35 x 5 - 175
= 175 - 175
= 0
e) 76 x 102 - 76 x 2
= 76 x ( 102 - 2 )
= 76 x 100
= 7600
c) 85 x 94 + 95 x 2 + 170 x 2
= 7990 + 2 x ( 95 + 170 )
= 7990 + 2 x 265
= 7990 + 530
= 8520
48 x 56 + 28 x 104
= 2688 + 2912
= 5600
g) 206 x 12 - 206 - 206
= 2472 - 206 - 206
= 2266 - 206
= 2060
![](https://rs.olm.vn/images/avt/0.png?1311)
a,42.99+42
=42.99+42.1
=42.(99+1)
=42.100
=4200
b,28:4-12:4
=7-3
=4
Cách 2:
28:4-12:4
=(28-12):4
=16:4
=4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+\dfrac{3}{4}=\dfrac{28}{6}+\dfrac{1}{2}\\ x+\dfrac{3}{4}=\dfrac{31}{6}\\ x=\dfrac{31}{6}-\dfrac{3}{4}\\ x=\dfrac{53}{12}\)
\(x+\dfrac{3}{4}=\dfrac{28+3}{6}=\dfrac{31}{6}\Leftrightarrow x=\dfrac{31}{6}-\dfrac{3}{4}=\dfrac{62-9}{12}=\dfrac{53}{12}\)
28 : x + 12 : x = 5
( 28 + 12 ) : x = 5
40 : x = 5
x = 40 : 5
x = 8