D=\(\dfrac{4}{11\cdot16}\)+\(\dfrac{4}{16\cdot21}\)+...+\(\dfrac{4}{61\cdot66}\)
D=\(\dfrac{4}{5}\)(\(\dfrac{1}{11}\)-\(\dfrac{1}{16}\)+\(\dfrac{1}{16}\)-\(\dfrac{1}{21}\)+...+\(\dfrac{1}{61}\)-\(\dfrac{1}{66}\))
D=\(\dfrac{4}{5}\)(\(\dfrac{1}{11}\)-\(\dfrac{1}{66}\))
D=\(\dfrac{4}{5}\)x\(\dfrac{5}{66}\)=\(\dfrac{2}{33}\)
\(\dfrac{7}{11.16}+\dfrac{7}{16.21}+\dfrac{7}{21.26}+.....+\dfrac{7}{61.66}\)
\(B=\frac{5}{11.16}+\frac{5}{16.21}+...+\frac{5}{61.66}\)
Tính nhanh
1. 2100+299+298+297+.......+22+2
2. A=4/5.7 + 4/7.9 +......+4/59.61
3. C= 1/10.11+1/11.12 +......+ 1/99.100
4. D=5/11.16 + 5/16.21 + ......+5/61.66
5. 2100-299+298-297
Tìm x biết {2/(11.16)+2/(16.21)+2/(21+26)+...+2/(231.236)}.x=45/1298
Tính :
a, \(\frac{15}{1.6}.\frac{15}{6.11}.\frac{15}{11.16}...\frac{15}{2011.2016}\)
b, \(\frac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}:\sqrt{\frac{25}{9}}\)
Tính tổng: D = 1^4 +2^4 + 3^4 +...+ n^4
bài 1: tính nhanh
a, (100-13).(100-23).(100-33)..........(100-503)
b, \(\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}+...........+\frac{5^2}{56.61}\)
c, \(2^{100}-2^{99}+2^{98}-2^{97}+.......+2^2-2^1\)
d, \(2015^{\left(1.4.9.6\right).\left(1.4.9.7\right).\left(1.4.9.8\right)....\left(1.9.9.9\right)}\)
bài 2: Tính
a, \(A=\left(-1\right).\left(-1\right)^2.\left(-1\right)^3.\left(-1\right)^4.\left(-1\right)^5.........\left(-1\right)^{99}\)
b, \(B=512-\frac{512}{2}-\frac{512}{2^2}-\frac{512}{2^3}-........-\frac{512}{2^{10}}\)
Bài 1 : Tính
a) A = \(\left(\dfrac{2}{3}+\dfrac{3}{4}-\dfrac{7}{12}\right):\left(\dfrac{55}{123}+\dfrac{555}{1234}+\dfrac{5555}{12345}\right)\)
b) B = \(\dfrac{5^2}{1.6}+\dfrac{5^2}{6.11}+\dfrac{5^2}{11.16}+...+\dfrac{5^2}{101.106}\)
c) C = \(\dfrac{2x^2+3x-1}{3x-2}\) với \(\left|x-1\right|=2\)
a, 3^17 : 3 ^ 15 - 4^12 . (1/2)^20 - | -12 | : căn bậc hai của 36 - 11 - 1
b, 11/1.6 + 11/6.11 + 11/11.16 + ....... + 11/2011.2016
