The first argument to int for indefinite integration must be of type algebraic. In other words, it must be an expression and cannot be any of the following: an operator, procedure, equation, set, list, Array, or table.

Example 1

The command int cannot take an equation as the first argument.

Solution:

Instead, try the following

Example 2

In this example, the functional operator passed as the first argument will cause an error.

Solution 1:

Use the expression $x^2$ for the first argument instead.

Solution 2:

Instead, define the function $f$, then use $f\left(x\right)$ as the first argument.

Example 3

The same error can occur when using the 2-D math integral notation:

Solution:

As in the previous example, you can either use an expression or define the function $f$, then use $f\left(x\right)$ as the first argument.