Question

Which of the following is not a linear equation in one variable? Why?
$2x - 1 = \dfrac{3}{2}$
$x + 3y = 5$
$a = 0$

Answer 1

Hint: Check for the number of variables and the highest degree of it.

Consider the given equation,
$2x - 1 = \dfrac{3}{2}$
We can see that there is only one variable and the highest order of the variable is $1$. Therefore, this is a linear equation in one variable.
Consider the second equation,
$x + 3y = 5$
Here, the highest degree of the variable is $1$, but there are two variables $x$ and $y$.Therefore, this is not a linear equation in one variable.
Consider the third equation,
$a = 0$
Here, only one variable is given and the highest order of the variable is $1$. Therefore, this is a linear equation in one variable.

Note: In these questions, check the number of variables, and then find the highest order of the variable.