Typically, this error occurs in Worksheet mode using 1-D Math.  For example, multiplication requires a * sign. For more operators, see arithmetic operator.

Also, all functions require parentheses around their arguments.

Example 1

Solution

Important: Implicit multiplication is permitted with 2-D Math input.

Functions require parentheses around their arguments.

Example 2

Solution

arithmetic operators, functions, 1-D versus 2-D Math