Tìm a:
A= \(\dfrac{1}{1x4}\)+\(\dfrac{1}{1x7}\)+\(\dfrac{1}{7x10}\)+.....+\(\dfrac{1}{100x103}\)
 

\(\dfrac{3}{4}\):x+\(\dfrac{1}{2}\):\(\dfrac{1}{4}\)=4
Tìm x

Tìm x: x+1+\(\dfrac{1}{3}\)+\(\dfrac{1}{9}\)+\(\dfrac{1}{27}\)+\(\dfrac{1}{81}\)=2

Tìm x: x- (\(\dfrac{2+2+2+2 }{3+15+35+63}\))= \(\dfrac{1}{9}\)

Tính nhanh: A= 13,7 x 18+82 x10,5 +82x3,2

Tìm a: 0,75 : (0,2-0,125)<a<11,05
 

Tính nhanh: 89 : 0,2 +89 + 89 :0,25

a) (58,76 - 7,75 x 2 + 72,72 : 3) : 13,5
b) (4,578: 3,27+ 0,872: 2,18) x 6,04 - 3,241