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A = 1 . 3 + 3 . 5 + 5 . 7 + ... + 49 . 51
A=1*51
A=
B = 2 . 4 + 4 . 6 + 6 . 8 + ... + 98 . 100
B=2*100
B=200
C = 1 . 4 + 4 . 7 + 7 . 10 + ... + 301 . 304
C=1*304
C=304
D = 1 + 1 . 1! + 2 . 2! + 3 . 3! + ... + 100 . 100!
D=1*100!
D=100!
E = 22 + 42 + ... + ( 2n )2
E=\(2^2\cdot2n^2\)
E=\(2n^4\)
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a,\(\frac{1}{2}+\frac{3}{4}-\frac{3}{4}+\frac{4}{5}\)
=\(\frac{1}{2}+\frac{3}{4}+\frac{-3}{4}+\frac{4}{5}\)
=\(\left(\frac{3}{4}+\frac{-3}{4}\right)+\frac{1}{2}+\frac{4}{5}\)
= \(0+\frac{1}{2}+\frac{4}{5}=\frac{13}{10}\)
Nhiều quá bạn ơi
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(1) 5/2 x (3/4 - 1/3) -11/12+1/4 = 5/2 x (9/12-4/12) -11/12 +3/12=5/2 x 5/12 -11/12 +3/12 = 25/24 - 11/12 +3/12=25/24 -22/24 + 6/24=9/12=3/4
(2) 11/12 : (4/10 + 3/5) + (5/6 - 1/2) x2/3
= 11/12 : (4/10 + 6/10) + (5/6-3/6) x 2/3
= 11/12:1 +1/2 x 2/3
= 11/12 + 2/3 =11/12+8/12 = 19/12
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\(\dfrac{1}{4}\) + 2.(3\(x\) - \(\dfrac{2}{3}\)) = 1
2.(3\(x\) - \(\dfrac{2}{3}\)) = 1 - \(\dfrac{1}{4}\)
2.(3\(x\) - \(\dfrac{2}{3}\)) = \(\dfrac{3}{4}\)
3\(x\) - \(\dfrac{2}{3}\) = \(\dfrac{3}{4}\): 2
3\(x\) = \(\dfrac{3}{8}\) + \(\dfrac{2}{3}\)
3\(x\) = \(\dfrac{25}{24}\)
\(x\) = \(\dfrac{25}{24}\) : 3
\(x\) = \(\dfrac{25}{72}\)
Vậy \(x\) = \(\dfrac{25}{72}\)