M=54-1/2(1+2)-1/3(1+2+3)-1/4(1+2+3+4)-....-1/12(1+2+....+12)
Tính nhanh:
a)\(A=\frac{1}{2015}-\frac{1}{2015.2014}-\frac{1}{2014.2013}-...-\)\(\frac{1}{3.2}-\frac{1}{2.1}\)
b)\(B=54-\frac{1}{2}.\left(1+2\right)-\frac{1}{3}.\left(1+2+3\right)\)\(-...-\frac{1}{12}.\left(1+2+3+..+12\right)\)
Giải Hộ Mình Pls
1)tìm x
a)(1/3-5/6.x)^3+21/54=5/6
b)1/12-1/3(1/2.x-1)^4=1/16
c)(3/5)^x-1+5.(3/5)^x-1=54/25
d)(2/3)^x+(2/3)^x+2=101/243
2) so sánh
a)1/27^11 và 1/81^8
b)1/3^99 và 1/11^21
1)tìm x
a)(1/3-5/6.x)^3+21/54=5/6
b)1/12-1/3(1/2.x-1)^4=1/16
c)(3/5)^x-1+5.(3/5)^x-1=54/25
d)(2/3)^x+(2/3)^x+2=101/243
2) so sánh
a)1/27^11 và 1/81^8
b)1/3^99 và 1/11^21
Tìm M, biết:
M = 54-\(\frac{1}{2}\). ( 1+2 ) - \(\frac{1}{3}\). ( 1+2+3 ) -\(\frac{1}{4}\)- ( 1+2+3+4) - ... - \(\frac{1}{12}\). ( 1+2+3+...+12)
tính:
1/2 x (1+2) - 1/3 x (1+2+3) - ... - 1/12 x (1+2+3+...+12)
tính
B=\(\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+...+\frac{1}{12}\left(1+2+3+...+12\right)\)
B = 1 + 1/2(1+2)+1/3(1+2+3)+...+ 1/12(1+2+3+..+12)
bài 1: tính:
a,1/5-1/2+/-1/4/
b,/-1/4/-3+3/4
c,3/4- 1 2 trên 3 (hỗn số)+/-1 1 trên 6/-2
d,(11/12-15/3+1/12-1/3):2/3
