Question

Select the property of equality used to arrive at the conclusion If x= 3, then x2 = 3x

Answer 1

You used the fact that you can multiply both sides of an equality by the same, non-zero constant.

So, if you start with the trivial equality

$x=x$

you can multiply both sides by 3:

$3x=3x$

But if $x=3$, $3x$ becomes $3\cdot 3$, which is $3^2$. So, we have

$3^2=3\cdot 3$

which leads to

$x^2=3x$

if you recall that $x=3$