B=4/3+10/9+28/27+...+3^98+1/3^98
1) \(B=\dfrac{1}{2^3}+\dfrac{1}{3^3}+\dfrac{1}{4^3}+\dfrac{1}{5^3}+...+\dfrac{1}{500^3}< \dfrac{1}{4}\)
2) \(D=\dfrac{4}{3}+\dfrac{10}{9}+\dfrac{28}{27}+...+\dfrac{3^{98}+1}{3^{98}}< 100\)
Cho M = \(\frac{4}{3}\) + \(\frac{10}{9}\) + \(\frac{28}{27}\) + ... + \(\frac{3^{98^{^{ }}}+1}{3^{98}}\) < 100
Chứng minh rằng:
1) B =\(\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{1}{6}+...+\dfrac{1}{19}>1\)
2) \(A=\dfrac{1}{5}+\dfrac{2}{5^2}+\dfrac{3}{5^3}+\dfrac{4}{5^4}+...+\dfrac{500}{5^{500}}<100\)
3) \(C=\dfrac{1}{2^3}+\dfrac{1}{3^3}+\dfrac{1}{4^3}+\dfrac{1}{5^3}+...+\dfrac{1}{500^3}<\dfrac{1}{4}\)
4) \(D=\dfrac{4}{3}+\dfrac{10}{9}+\dfrac{28}{27}+...+\dfrac{3^{98}+1}{3^{98}}<100\)
Làm giúp mình sớm nha! Thanks.
Bài 1: Tính một cách hợp lí:
1) 2155 - ( 174 + 2155 ) + ( -68 + 174 ) 7) -1911 - ( 1234 - 1911 )
2) -25 . 72 + 25 . 21 - 49 . 25 8) 156 . 72 + 28 . 156
3) 35 . ( 14 - 23 ) - 23 . ( 14 - 35 ) 9) 32. ( -39 ) + 16 . ( -22 )
4) 8154 - ( 674 + 8154 ) + ( -98 + 674 ) 10) -1945 - ( 567 - 1945 )
5) -25 . 21 + 25 . 72 + 49 . 25 11) 184 . 33 + 67 . 184
6) 27 . ( 13 - 16 ) - 16 . ( 13 - 27) 12) 44 . ( -36 ) + 22 . ( -28 )
1-2-3-4+ 5-6-7-8+9-10-11-12+.....+97 -98-99-100
1, A=1-2-3-4+5-6-7-8+9-10-11-12+.....+97-98-99-100
Bài 1 : Tính hợp lý
A=100+98+96+...+2 - 97 - 95 - ... - 1
B=1+2 - 3 - 4 + 5+6 - 7 - 8+9+10 - 11 - 12 +...-299 - 300 + 301 + 302
Bài 1.Tính
a.(1/2+1).(1/3+1).(1/4+1).…….….(1/99+1)
b.1:99/100:98/99:97/98:…………:2/3:1/2
Bài 2.Tìm x, biết
a.(1,16x).5,25/(10 5/9-7 ¼).2 2/7=75%
b.x+4/5.9-+4/9.13+4/13.17+................+4/41.45=-37/45
Giúp mik với , mik cảm ơn trước nka!!!