=703-2-289=703-291=412

AI GIÚP EM VỚI Ạ

\(#N\)

\(-\dfrac{11}{7}+\dfrac{13}{-2}+-\dfrac{6}{17}=-\dfrac{113}{14}+-\dfrac{6}{17}=-\dfrac{2005}{238}\)

\(\dfrac{13}{-8}+-\dfrac{7}{20}+\dfrac{3}{-8}=\left(-\dfrac{13}{8}+-\dfrac{3}{8}\right)+-\dfrac{7}{20}=-2+-\dfrac{7}{20}=-\dfrac{47}{20}\)

\(-\dfrac{4}{7}+\dfrac{11}{5}+\dfrac{1}{5}+-\dfrac{7}{3}=-\dfrac{4}{7}+\left(\dfrac{11}{5}+\dfrac{1}{5}\right)+-\dfrac{7}{3}=-\dfrac{4}{7}+\dfrac{12}{5}+-\dfrac{7}{3}=-\dfrac{53}{105}\)

\(\dfrac{7}{8}\) \(\times\) \(\dfrac{1}{6}\) + \(\dfrac{7}{8}\) \(\times\) \(\dfrac{2}{6}\) + \(\dfrac{7}{8}\) \(\times\) \(\dfrac{1}{2}\)

= \(\dfrac{7}{8}\) \(\times\) ( \(\dfrac{1}{6}\) + \(\dfrac{2}{6}\) + \(\dfrac{1}{2}\) )

= \(\dfrac{7}{8}\) \(\times\) ( \(\dfrac{3}{6}\) + \(\dfrac{1}{2}\))

=  \(\dfrac{7}{8}\) \(\times\) ( \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\))

= \(\dfrac{7}{8}\) \(\times\) 1

= \(\dfrac{7}{8}\)

    25 \(\times\) 5 \(\times\) 4 \(\times\)2  - 176

= (25 \(\times\) 4 ) \(\times\) ( 5 \(\times\) 2) - 176

= 100 \(\times\) 10 - 176

= 1000 - 176

= 824

\(\dfrac{7}{8}\times\dfrac{1}{6}+\dfrac{7}{8}\times\dfrac{2}{6}+\dfrac{7}{8}\times\dfrac{1}{2}\)

\(=\dfrac{7}{8}\times\left(\dfrac{1}{6}+\dfrac{2}{6}+\dfrac{1}{2}\right)\)

\(=\dfrac{7}{8}\times1\)

\(=\dfrac{7}{8}\)

__________________________ 

\(25\times5\times4\times2-176\)

\(=\left(25\times4\right)\times\left(4\times2\right)-176\)

\(=1000-176\)

\(=824\)

Chúc bạn học tốt

b: =20x(-2)+12x5

=-40+60

=20

câu cuối là 999,7650928....

rồi mà, câu 3 là 100 

gấp lắm!!!!

a) (135 - 35) . (-37) + 37 . (-42 - 58)

= 100 . 0 . (-100)

= 0

b) -65 . (87 - 17) - 87 . (17 - 65)

= -65 . 70 - 87 . (-48)

= -4550 - 135

= -4415

a, [ 58+(-42)]-(58-42)

 = 58 - 42 - 58 + 42

 = ( 58 - 58 ) + ( 42 - 42)​

 = 0+0=0

b, ( 65 - 35 ) - ( 35 + 27 )

  = 65 - 35 - 35 - 27

  = 65 - 70 -27

  = 65 - 97

  = -32

c, 3 . 5² - 176 : 2³

  =3 .25 - 176 : 8

  =  75 - 22

  =    53

d, 2² . 3 - 5 . 2³

  = 4 . 3  -  5 . 8

  =   12   -   40

  =       -28

g, 2020 - [ 39 - ( 5 - 1 )² ] - 2019

  = 2020 - [ 39 - 4² ] - 2019

  = ( 2020 -2019 ) - [ 39 - 16 ]

  =      1   -   23 

  =         -22

k, 2018 : [ 38 - ( 7 - 1 )² ] + 2018⁰

  = 2018 : [ 38 - 6² ] + 1

  = 2018 : [ 38 - 36 ] + 1

  = 2018 : 2 + 1

  = 1009 + 1 =1010

a)\(\left[58+\left(-42\right)\right]-\left(58-42\right)\)

=\(58-42-58+42\)

=\(0\)

b)\(\left(65-35\right)-\left(35+27\right)\)

=\(65-35-35+27\)

=\(-32\)

c)\(3.5^2-176:2^3\)

=\(75-22\)

=\(53\)

d)\(2^2.3-5.2^3\)

=\(2^2\left(3-10\right)\)

=\(-28\)

g)\(2020-\left[39-\left(5-1\right)^2\right]-2019\)

=\(1-\left(39-16\right)\)

=\(-22\)

k)\(2018:\left[38-\left(7-1\right)^2\right]+2018^0\)

=\(2018:2+2018^0\)

=\(1010\)

x-7=-5

=>x=-5+7=2

x+2=0

=>x=0-2=-2

\(\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)

=>\(3x-16=\frac{2\cdot7^4}{7^3}=2\cdot7=14\)

=>3x=16+14=30

=>x=30/3=10

|x-5|=|-7|

=>x-5=7 hoặc x-5=-7

=>x=12 hoặc x=-2

x-[42+(-28)]=-8

=>x-14=-8

=>x=-8+14

=>x=6

128-3(x+4)=23

=>3(x+4)=128-23=105

=>x+4=35

=>x=35-4=31

4-(7-x)=x-(13-4)

=>4-7+x=x-9

=>x-3=x-9

=>-3=-9(vô lý)

=>x∈∅

Bài 2:

S1=1+2+...+999

\(=\frac{999\left(999+1\right)}{2}=999\cdot\frac{1000}{2}\)

\(=999\cdot500=499500\)

S1=10+12+...+2010

Số số hạng của dãy là:

(2010-10):2+1=2000:2+1=1001(số)

Tổng của dãy số là:

\(S_1=\left(2010+10\right)\cdot\frac{1001}{2}=2020\cdot\frac{1001}{2}=1001\cdot1010=1011010\)