Question

2/x+1/2x=7
x=?

Answer 1

multiply through by x(x+1). You will get a quadratic which you can hopefully use the quadratic formula on to find x.

Answer 2

oh sorry, multiply through by x only

Answer 3

and you won't get a quadratic. It's a linear equation in x. Here is how you solve it:
\[\frac{2}{x} + \frac{1}{2x} = 7\]
multiply through by 2x to get:
\[4 + 1 = 14x\]
giving \[x=\frac{5}{14}\]