Question

Bài 1 : không tính tổng xét xem tổng sau có chia hết cho 6 không ?

a) 4251+3030+12

b) 3257 + 4092

c) 3141- 627

d) 5173 - 222

Bài 2 : Tìm x :

a)\(x-\dfrac{3}{20}=\dfrac{1}{4}\)

b)\(\dfrac{5}{6}x+\dfrac{3}{4}=\dfrac{1}{3}\)

Answer 1

Bài 2: Giải:

a, \(x-\dfrac{3}{20}=\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{1}{4}+\dfrac{3}{20}\)

\(\Rightarrow x=\dfrac{5}{20}+\dfrac{3}{20}\)

\(\Rightarrow x=\dfrac{8}{20}=\dfrac{1}{5}\)

Vậy \(x=\dfrac{1}{5}\)

b, \(\dfrac{5}{6}x+\dfrac{3}{4}=\dfrac{1}{3}\)

\(\Rightarrow\dfrac{5}{6}x=\dfrac{1}{3}-\dfrac{3}{4}\)

\(\Rightarrow\dfrac{5}{6}x=-\dfrac{5}{12}\)

\(\Rightarrow x=-\dfrac{5}{12}:\dfrac{5}{6}\)

\(\Rightarrow x=-\dfrac{1}{2}\)

Vậy x = \(-\dfrac{1}{2}\)