The question asked me to solve
$\dfrac {x^2+2x-8}{x^2-x-2}=3$
The answer is $x=0.5$, which I worked out, but in the answers it says that I must state the condition that $x≠2$ to get full marks. Why is this condition present? How can I recognise when a condition exists, when I encounter similar problems?
When solving this equation you assume that $x^2-x-2\ne{0}\implies{}x\ne{}-1,2$. In general while solving an equation make sure that the denominator is not equal $0$.