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A = \(\dfrac{1}{2}\) + \(\dfrac{1}{6}\) + \(\dfrac{1}{12}\) + \(\dfrac{1}{20}\)+...+ \(\dfrac{1}{812}\) + \(\dfrac{1}{870}\)
A = \(\dfrac{1}{1.2}\) + \(\dfrac{1}{2.3}\) + \(\dfrac{1}{3.4}\) + \(\dfrac{1}{4.5}\)+...+ \(\dfrac{1}{28\times29}\)+ \(\dfrac{1}{29\times30}\)
A = \(\dfrac{1}{1}\) - \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{4}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{5}\) +...+\(\dfrac{1}{28}\)-\(\dfrac{1}{29}\)+ \(\dfrac{1}{29}\) - \(\dfrac{1}{30}\)
A = 1 - \(\dfrac{1}{30}\)
A = \(\dfrac{29}{30}\)
4,58* 6,7+ 4,58* 28,3+ 4,58* 65
= 4,58 x ( 6,7 + 28,3 + 65 )
= 4,58 x 100
= 458
4,58 * 6,7 + 4,58 * 28,3 + 4,58 * 65
= 4,58 * (6,7+28,3+65)
=4,58 * 100
= 458
a) (137x25-25x37):10
=25x(137-37):10
=25x100:10
=2500:10
=250
b) 2/7x21/4-2/7:13/4
=2/7x21/4-2/7x4/13
=2/7x(21/4-4/13)
=2/7x257/52
=257/182
c)(124x237+152):(870+235x122)
=(29388+152):(870+28670)
=29540:29540
=1
a) (137 x 25 - 25 x 37 ) : 10 = (25 x (137 - 37) ) : 10
= (25 x 100) : 10
= 2500 : 10
= 250
a)=(3425-925):10
=25200:10
=250
b)=3/2-8/91
=257/182
c)=(29388+152):(870+28670)
=29540:29540
=1
d)=1161+1539/72
=2700/72=75/2
e)=10/77+45/77x9/7
=10/77+405/539
=475/539
li ke cho mình nha Lam Le thi
