TITLE: Why does cancelling change this equation?
QUESTION [36 upvotes]: The equation
$$2t^2 + t^3 = t^4$$
is satisfied by $t = 0$
But if you cancel a $t^2$ on both sides, making it
$$2 + t = t^2$$
$t = 0$ is no longer a solution.
What gives? I thought nothing really changed, so the same solutions should apply.
Thanks

REPLY [4 votes]: If $ t = 0 $, then dividing both sides by $ t^2 $ would mean dividing by zero.