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31 tháng 12 2021

-1989 nhé em

31 tháng 12 2021
3^3 + 80 ÷ (17 - 13)^2 - 2021 = 1989
18 tháng 12 2023

a) 17 + 15 + (-27)

= (17 - 27) + 15

= -10 + 15

= 5

b) 13.75 + 25.13 - 300

= 13.(75 + 26) - 300

= 13.100 - 300

= 1300 - 300

= 1000

c) 80 - (4.5² - 5.2³) + 2021⁰

= 80 - (4.25 - 5.8) + 1

= 80 - (100 - 40) + 1

= 80 - 60 + 1

= 20 + 1

= 21

1) Ta có: \(\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{7}{25}\cdot\dfrac{5}{7}\right)\)

\(=\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{1}{5}\right)\)

=0

2) Ta có: \(\dfrac{8}{17}\cdot\dfrac{4}{15}+\dfrac{8}{17}\cdot\dfrac{22}{15}-\dfrac{8}{15}\cdot\dfrac{9}{17}\)

\(=\dfrac{8}{17}\left(\dfrac{4}{15}+\dfrac{22}{15}-\dfrac{9}{15}\right)\)

\(=\dfrac{8}{17}\cdot\dfrac{15}{15}=\dfrac{8}{17}\)

3) Ta có: \(\dfrac{2021}{2}\cdot\dfrac{1}{3}+\dfrac{4042}{4}\cdot\dfrac{1}{5}+\dfrac{6063}{3}\cdot\dfrac{22}{15}\)

\(=\dfrac{2021}{2}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)+2021\cdot\dfrac{22}{15}\)

\(=\dfrac{2021}{2}\cdot\dfrac{8}{15}+\dfrac{2021}{2}\cdot\dfrac{44}{15}\)

\(=\dfrac{2021}{2}\cdot\dfrac{52}{15}\)

\(=\dfrac{52546}{15}\)

4) Ta có: \(\dfrac{4}{7}\cdot\dfrac{2}{13}+\dfrac{8}{13}:\dfrac{7}{4}+\dfrac{4}{7}:\dfrac{13}{2}+\dfrac{4}{7}\cdot\dfrac{1}{13}\)

\(=\dfrac{4}{7}\left(\dfrac{2}{13}+\dfrac{8}{13}+\dfrac{2}{13}+\dfrac{1}{13}\right)\)

\(=\dfrac{4}{7}\)

2 tháng 7 2021

cảm ơn nhé

vui

\(=\left(\dfrac{1}{8}+\dfrac{2}{5}-\dfrac{3}{40}\right):\left[\dfrac{80}{7}+\dfrac{17}{2}\cdot\dfrac{-877}{84}\right]\)

\(=\dfrac{5+16-3}{40}\cdot\dfrac{168}{-4489}=\dfrac{9}{20}\cdot\dfrac{-168}{4489}=\dfrac{-378}{22445}\)

a: \(=\dfrac{54-34}{189-119}=\dfrac{20}{70}=\dfrac{2}{7}\)

b: \(=\dfrac{6+6\cdot4+6\cdot49}{15+15\cdot4+15\cdot49}=\dfrac{6}{15}=\dfrac{2}{5}\)

c: \(=\dfrac{13\left(3-18\right)}{40\left(15-2\right)}=\dfrac{-15}{40}=-\dfrac{3}{8}\)

a: M=-2021+2021-68-68+17

=-119

b: B=(-1)+(-1)+...+(-1)

=-1x500

=-500

c: C=(1-2-3+4)+(5-6-7+8)+...+(997-998-999+1000)

=0

21 tháng 1 2022

Cảm ơn bạn nhé

23 tháng 9 2021

\(x=\dfrac{\sqrt[3]{\left(2+\sqrt{3}\right)^3}\left(2-\sqrt{3}\right)}{\sqrt[3]{9+4\sqrt{5}}+\sqrt[3]{9-4\sqrt{5}}}=\dfrac{1}{\sqrt[3]{9+4\sqrt{5}}+\sqrt[3]{9-4\sqrt{5}}}\)

Đặt \(A=\sqrt[3]{9+4\sqrt{5}}+\sqrt[3]{9-4\sqrt{5}}\)\(\Leftrightarrow A^3=18+3\sqrt[3]{\left(9-4\sqrt{5}\right)\left(9+4\sqrt{5}\right)}\left(\sqrt[3]{9+4\sqrt{5}}+\sqrt[3]{9-4\sqrt{5}}\right)\\ \Leftrightarrow A^3=18+3A\sqrt[3]{1}\\ \Leftrightarrow A^3-3A-18=0\\ \Leftrightarrow A=3\\ \Leftrightarrow X=\dfrac{1}{3}\\ \Leftrightarrow Q=\left[3\left(\dfrac{1}{3}\right)^3-\left(\dfrac{1}{3}\right)^2-1\right]^{2021}=\left(\dfrac{1}{9}-\dfrac{1}{9}-1\right)^{2021}=\left(-1\right)^{2021}=-1\)

a: 3/7=18/42

5/6=35/42

b: 5/17=15/51

9/51=9/51

c: 3/8=9/24

5/6=20/24

g: 7/30=28/120

13/60=26/120

9/40=27/120

14 tháng 6 2017

a) 23 . 17 - 23 . 14

= 23(17-14)

=23. 3= 24

b) 80 - ( 4 . 5 - 3 . 23 )

= 80- 22. (5-3.2)= 80- 22.(-1)

= 80- 4.(-1)= 80- (-4)= 84

c) 35 - { 12 - [ -14 + ( -2) }

= 35 - { 12 - (-16) }

=35- 28= 7

d) 49 - ( -45) - 23

= 94-23= 71

e) 13 - 18 - ( -42) - 15

= -5 -(-42) -15

= -20+42= 22

g) -452 - ( -67 + 75 - 452 )

= -452- (8-452)

= -452 -(- 444)= -8

h) |31−17|−|13−52|

= 14- 39= -25

14 tháng 6 2017

80 -(4.52 -3.23)

= 80- (4.25- 3.8)

= 80- (100-24)

= 80-76= 4

19 tháng 7 2016

ôi dào bài này dễ thôi

19 tháng 7 2016

a/= -2.4 == 8

b/ = -2.5+21=11