1. (627- 138) : ( 3 x X :2) = 163

2. (X-1)x3+ 3/20 +3/13+3/2015/5+5/20+5/13+5/20+5/2015

tìm x biết 3+3/20+3/15+3/2015 

              5+5/20+5/15+5/2015=5/3

\( 3+3/20+3/15+3/2015/5+5/20+5/15+5/2015\)

tìm x biết 

a, -12 ( x - 5 ) + 7 ( 3 - x ) = 2015

b, 20 ( x - 4 ) - 5 ( x + 3 ) - 15x = 20

c, I 2x - 5 I = 13

d, ( x + 3) ( x - 7 ) < 0

1 tính

a,( 17/20+19/21). 31/20 (17/20+19/21). (-31/20)

b, 3/4.15/2+15/8.(-3) + 199/200

c, (199/200+201/202+2015/2014). (1/2+2/3+ -7/6)

d, a(b+1/5) -a ( 6/5 + b ) với a= 2015/2015 ; b= 2000

Tính:

a) 2^5 x 13^12 x 7^8 : 27 x 13^10 x 7^9 

b) 2^n x 11 x 3 : 6^n x 3

c) 5^5 x 7 x 9^5 : 15^10

d) 7 x 8^10 x 27^9 - 8 x 9^13 x 2^27 : 7 x 6^26 x 2^2 - 2^4 x 8^3 x 27^9

e) 2^2^1^2015

f) 2015^0^2015^0^2015

a,A=1+2+3+4+. + 2014 b,B=1+3+5+7+. +2013 c,C=2+4+6+8+. +2014 d,1+4+7+10+13+. +2014 e, 5+10+15+20. +2015 Làm theo công thức: (Số cuối - số đầu): khoảng cách +1

Tính:

a) 2^5 x 13^12 x 7^8 : 2^7 x 13^10 x 7^9 

b) 2^n x 11 x 3 : 6^n x 3

c) 5^5 x 7 x 9^5 : 15^10

d) 7 x 8^10 x 27^9 - 8 x 9^13 x 2^27 : 7 x 6^26 x 2^2 - 2^4 x 8^3 x 27^9

e) 2^2^1^2015

f) 2015^0^2015^0^2015

Tính hợp lý:

A= 21.\(10^2\)-11.100+90.\(10^2\)+\(2^2\).\(5^2\).125.16

B= \(\dfrac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^9.6^{19}-7.2^{29}.27^6}\)

C= 3+5-7-9+11+13 -13-17+19+...+2013-2015-2017+2019+2020