Sửa đề: \(\left(46\times369+46\right)-\left(268\times45+268\right)\)

\(=46\times\left(369+1\right)-268\times\left(45+1\right)\)

\(=46\times\left(370-268\right)\)

\(=46\times102\)

\(=4692\)

Bài 3:

a: \(=\left(-47+47\right)+\left(200-400\right)=-200\)

b: \(=\left(-2\right)+\left(-2\right)+\left(-2\right)=-6\)

c: \(=25\left(-19-81\right)=25\cdot\left(-100\right)=-2500\)

d: \(=17\cdot28-17\cdot32-28\cdot17+28\cdot32=32\cdot11=352\)

e: \(=12-57+57-12=0\)

Lười quá sr bn -.-

Bạn nên rút gọn các ps rồi tính, mik làm r nên mik chỉ bn còn đâu bn tự làm đi ạ=))

2 . 14 . 98 + 7 . 4 . 32 - 28 . 30

= 28 . 98 + 28 . 32 - 28 . 30

= 28 . ( 98 + 32 - 30 )

= 28 . 100

= 2800

\(2.14.98+7.4.32-28.30\\ =\left(2.14\right).98+\left(7.4\right).32-28.30\\ =28.98+28.32-28.30\\ =28.\left(98+32-30\right)\\ =28.100\\ =2800\)

a thì cộng số âm trc rồi cộng số dương sau

\(a,=-17+91-91+17+2011=\left(-17+17\right)+\left(91-91\right)+2011\)

\(=0+0+2011=2011\)

b)\(=\dfrac{4}{7}+\dfrac{1}{6}-0,375.4=\dfrac{31}{42}-\dfrac{3}{2}=-\dfrac{16}{21}\)

\(b)\) \(\dfrac{4}{7}\) + \(\dfrac{5}{6}\) : \(5\) \(- 0,375 .(-2)\)²\(=\) \(\dfrac{4}{7}\) + \(\dfrac{1}{6}\) - \(0,375\) . \(4\)

= \(\dfrac{4}{7}\) + \(\dfrac{1}{6}\) - \(\dfrac{3}{2}\) = \(\dfrac{4.6}{42}\) +  \(\dfrac{1.7}{42}\) - \(\dfrac{3.21}{42}\) = \(-\)\(\dfrac{16}{21}\)

\(\dfrac{5}{7}\).\(\dfrac{-3}{11}\)-\(\dfrac{5}{7}\).\(\dfrac{8}{11}\)+1\(\dfrac{5}{7}\)

= \(\dfrac{5}{7}\).(\(\dfrac{-3}{11}\) - \(\dfrac{8}{11}\)) + 1\(\dfrac{5}{7}\)

= \(\dfrac{5}{7}\). -1             + 1\(\dfrac{5}{7}\)

= \(\dfrac{-5}{7}\)               +1\(\dfrac{5}{7}\)

= -1

\(\dfrac{5}{7}.-\dfrac{3}{11}-\dfrac{5}{7}.\dfrac{8}{11}+1\dfrac{5}{7}\)

\(=\dfrac{5}{7}.\left(\dfrac{3}{11}-\dfrac{8}{11}\right)+1\dfrac{5}{7}\)

\(=\dfrac{5}{7}.\left(-1\right)+1\dfrac{5}{7}\)

\(=1\)

15 - (+72) + (+75) + (+72)

= 15 - 72 + 75 + 72

= -57 + 75 + 52

= 18 + 52

= 70

- Giúp chúng ta chủ động, tiết kiệm thời gian, công sức.

- Đạt kết quả cao trong công việc.

- Không cản trở, ảnh hưởng đến người khác.

Làm việc có kế hoạch chính là tiết kiệm thời gian.

1) A=\(\dfrac{7}{1.3}+\dfrac{7}{3.5}+\dfrac{7}{5.7}+...+\dfrac{7}{99.101}\)=\(\dfrac{7.2}{1.3.2}+\dfrac{7.2}{3.5.2}+\dfrac{7.2}{5.7.2}+...+\dfrac{7.2}{99.101.2}\)=

\(\dfrac{7}{2}\left(\text{​​}\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{99.101}\right)\)=

\(\dfrac{7}{2}\left(\text{​​}1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}...+\dfrac{1}{99}-\dfrac{1}{101}\right)\)=

\(\dfrac{7}{2}\left(\text{​​}1-\dfrac{1}{101}\right)\)=\(\dfrac{7}{2}.\dfrac{100}{101}=\dfrac{350}{101}\)

2) A=\(\dfrac{1}{2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}\)=\(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\)

=\(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{16}\)=\(1-\dfrac{1}{16}=\dfrac{15}{16}\)