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a, \(\dfrac{7}{22}\) - \(\dfrac{15}{23}\) + \(\dfrac{2022}{2023}\) - \(\dfrac{8}{23}\) + \(\dfrac{15}{22}\)
= ( \(\dfrac{7}{22}\) + \(\dfrac{15}{22}\)) - ( \(\dfrac{15}{23}+\dfrac{18}{23}\)) + \(\dfrac{2022}{2023}\)
= \(\dfrac{22}{22}\) - \(\dfrac{23}{23}\) + \(\dfrac{2022}{2023}\)
= 1 - 1 + \(\dfrac{2022}{2023}\)
= \(\dfrac{2022}{2023}\)
b, - \(\dfrac{2}{11}\) + 5\(\dfrac{5}{6}\) ( 14\(\dfrac{1}{5}\) - 11\(\dfrac{1}{5}\)): 5\(\dfrac{1}{2}\)
= - \(\dfrac{2}{11}\) + \(\dfrac{35}{6}\) ( \(\dfrac{71}{5}\) - \(\dfrac{56}{5}\)) : \(\dfrac{11}{2}\)
= - \(\dfrac{2}{11}\) + \(\dfrac{35}{6}\) . \(\dfrac{15}{5}\) : \(\dfrac{11}{2}\)
= - \(\dfrac{2}{11}\) + \(\dfrac{35}{2}\) \(\times\) \(\dfrac{2}{11}\)
= - \(\dfrac{2}{11}\) + \(\dfrac{35}{11}\)
= \(\dfrac{33}{11}\)
= 3
c, 2000 + { 20 - [ 4.20220 - (32 + 5):2] }
= 2000 + { 20 - [ 4.1 - (9+5):2]}
= 2000 + { 20 - [ 4 - 14 : 2 ]}
= 2000 + { 20 - [ 4 -7]}
= 2000 + { 20 - (-3)}
= 2000 + 23
= 2023
Lời giải:
$A=(21-23)+(25-27)+....+(2021-2023)$
$=(-2)+(-2)+...+(-2)$
Số lần xuất hiện của $-2$ là: $[(2023-21):2+1]:2=501$
$A=501(-2)=-1002$
$B=(1-2-3+4)+(5-6-7+8)+....+(1997-1998-1999+2000)$
$=0+0+0+...+0=0$
\(27.77+24.27-27\)
\(=27.\left(77+24-1\right)\)
\(=27.100\)
\(=2700\)
\(174\div\left\{2\left[36+\left(4^2-23\right)\right]\right\}\)
\(=174\div\left\{2\left[36+\left(16-23\right)\right]\right\}\)
\(=174\div\left\{2\left[36+\left(-7\right)\right]\right\}\)
\(=174\div\left\{2.29\right\}\)
\(=174\div58\)
\(=3\)
\(3^2.4-\left[30-\left(5-2\right)^2\right]\)
\(=9.4-\left[30-3^2\right]\)
\(=36-\left[30-9\right]\)
\(=36-21\)
\(=15\)
\(A=4x4x...x4\left(2023.chũ.số.4\right)\)
\(A=4^{23}=4^{20}.4^3=\overline{....6}x\overline{....4}=\overline{....4}\)
\(B=3x15x23x...x2023\)
\(B=\overline{....5}\) (trong tích có các số có tận cùng bằng 5)
1:
a: =23/27-11/17+4/27+28/17
=23/27+4/27+28/17-11/17
=1+1=2
b: \(=\dfrac{2}{3}\cdot\left(\dfrac{7}{9}+\dfrac{2}{9}\right)-\dfrac{2}{9}\)
=2/3-2/9
=6/9-2/9
=4/9
c: \(=\dfrac{11}{5}\cdot\dfrac{7}{3}-\dfrac{1}{3}\cdot\dfrac{11}{5}\)
=11/5(7/3-1/3)
=11/5*2
=22/5
d: \(=\dfrac{3}{2}\cdot\dfrac{4}{3}\cdot...\cdot\dfrac{2024}{2023}=\dfrac{2024}{2}=1012\)
e: \(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot...\cdot\dfrac{2022}{2023}=\dfrac{1}{2023}\)
-7000
= [ 102. (-27) - 2023 ] - [ 23 . (-25) . 4 - 23 ]
= [ 100 . (-27) - 2023 ] - [ -2300 - 23 ]
= [ -2700 - 2023 ] - (-2323)
= -4723 - ( - 2323)
= -2400