Tim x biet 1+1/2(1+2)+1/3(1+2+3)+...+1/x(1+2+3+...+x)=115
Giup toi voi
tim x , biet :
1 ) 2017 - \ x - 2017 \ = x
2) -1/2 . ( 3x - 1 ) + 3/4 . ( 3-2x) = -3 . ( x/2 - 1 ) - ( 4/5) mu -1
1)tim x biet rang:
a)3^x-1=1/243
b)2^x+2^x+3=144
c)81^-2x.27x=9^5
2)tim tiep so ghang thu 5 cua day so sau:-1/a^2;2/a^3;-6/a^4;24/a^5;...
3)tim so tu nhien x biet :
a)4^x+4^x+3=4160
b)2^x-1+5.2^x-2=7/32
Tim x biet:
a.2|2x-3|=1/2
b.(x-1)^2=9/16
c.3/5(x-5/6)-1/2(3/2-1)=-1/4
d.1/3+1/6+1/10+......+2/x(x+1)=2015/2016
tim x biet (1/2+1/3+...+1/2014).x=2013/1+2012/2+...+1/2013
Tim x biet
(X+1)×(x+2)<0 x-2/3x+2 <0
(-3+3/x -1/3) ÷ (1+2/3+2/5)=-5/4
tim x thuoc z biet
a,1/(1×2) + 1/(2×3) + ... + 2/(x(x+1)) = 2005/2010
biet rang 1^2+2^2+3^2+....+10^2=385.Tim x biet x+10^2+12^2+14^2+...+20^2=2011+1^2+3^2+...+9^2
