1. Tìm x, biết :
a) 9 + x/ 15 - x = 5/7
b) x +x :5 * 9,5 + x : 4 * 10 = 315
2. Tính nhanh:
2018 *2017-1/2016*2018+201
a) ( x - 21 x13) : 11 = 39
b) ( x - 21) x 13 : 11 = 39
c) ( x - 5 ) x ( 2016 x 2017 + 2017 x 2018 ) = 1234 X 5678 x ( 636 -315 x 2) : 2018
A = 2017/2018 x 7/8 + 2017/2018 x 3/8 - 2017/2018 x 1/4
Tính nhanh
A= 2016 x 2017 +4034 / 2018 x 2019 - 4036
tìm x , biết :
\(\frac{x-2019}{2018}+\frac{x-2018}{2017}=\frac{x-2017}{2016}+\frac{x-2016}{2015}\)
Tính nhanh :
a,2017 x 2021 - 4031 / 2020 + 2017 x 2018
b,2017 x 2019 + 1009 / 2019 x 4035 - 1
bài 1: tính
(2019 – 2018 + 2017 – 2016 + 2015 + ....... – 4 + 3 – 2) x ( 100 – 25 x 2 x 2)
cho A =1+2^2018+3^2017+4^2016+...+2018^2+2019,B=1+2^2017+3^2016+...+2017^2+2018,chứng tỏ giá trị biểu thức A-3B dương