Question

tìm số nguyên :

\(\dfrac{x}{5}\)=\(\dfrac{x+6}{15}\)

Answer 1

Giải:

\(\dfrac{x}{5}=\dfrac{x+6}{15}\)

\(\Leftrightarrow x.15=5\left(x+6\right)\)

\(\Leftrightarrow15x=5x+30\)

\(\Leftrightarrow15x-5x=30\)

\(\Leftrightarrow10x=30\)

\(\Leftrightarrow x=3\)

Vậy...

Answer 2

\(15\cdot x=5.\left(x+6\right)\)

\(15\cdot x=5\cdot x+5\cdot6\)

\(15\cdot x=5\cdot x+30\)

\(15\cdot x-5\cdot x=30\)

\(\left(15-5\right)\cdot x=30\)

\(10\cdot x=30\)

\(x=30\div10\)

\(x=3\)

Answer 3

Giải:

Theo đề bài ta có:

\(\dfrac{x}{5}=\dfrac{x+6}{15}\)

Vì 15=3.5⇒x+6=x.3

x.3=x+6

⇒x.2=6

⇒x=6:2

Vậy...........