Answer
The error is in the first step.
Work Step by Step
The given polynomial is
$=(x^2+x)-(2x^2-3x)$
Clear the parentheses.
$=x^2+x-2x^2+3x$
Group like terms.
$=x^2-2x^2+x+3x$
Combine like terms.
$=-x^2+4x$
Hence, the error is in the first step.
