1+1/3+1/6+1/10+....+1/X(X+1):2=1\(\frac{1991}{1943}\)
Tìm số tự nhiên x, biết : 1+1/3+1/6+1/10+.......+1/x.(x+1):2 = 1+1991/1993
Giúp mình nhóe
1+\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+.....+\frac{2}{x\left(x+1\right)}=1\frac{1989}{1991}\)
tìm x biết
a 1/5.8+1/8.11+1/11.14+...1/x(x+3)=101/1540
b 1+1/3+1/6+1/10+...1/x(x+1)=\(1\frac{1991}{1993}\)
tim x biet :
a )\(\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
b) \(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+1\right).2}=1\frac{1991}{1993}\)
Thực hiện phép tính
(x-1)(x^1994+x^1993+x^1992+x^1991+...+x^2+x+1)
(x+1) (x^1994-x^1993-x^1992-x^1991-...-x^2-x+1)
Giúp mk nha, mkcânf gấp
tim x biet
a.\(\frac{x+1}{10}+\frac{x+1}{11}=\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)
b.\(\frac{x+4}{1990}+\frac{x+3}{1991}=\frac{x+2}{1992}+\frac{x+1}{1993}\)
tìm x, biết :
a) 1/( x+1 ).( x+2 ) + 1/( x+2 ).( x+3 ) + 1/( x+3 ).( x+4 ) + ... + 1/( x+1999).( x+2000) = 1/x+200 = 1/5
b) 2/( x+1 ).( x+3 ) + 3/( x+3 ) .( x+6 ) + 4/( x+6 ).( x+10 ) + ... + 10/( x+45 ).( x+55 ) + 1/ x+55 = 1/6
tìm x biết
1) x=-1/2 + 3/4 2) x - 1/5 = 2/11 3) x - 5/6 = 16/42 + -8/56
4) x/5 = 5/6 + -19/30 5) |x| - 1/4 = 6/18 6)x = -1/2 +3/4
7) x/15 = 3/5 + -2/3 8)11/8 + 13/6 = 85/x 9) x - 7/8 = 13/12
10) x - -6/15 = 4/27 11) -\(\dfrac{-6}{12}\)+ x = 9/48 12) x - 4/6 = 5/25 + -7/15