Question

How do you solve `21x^2=12x` by factoring?

Answer 1

First subtract `12x` on both sides

Explanation:

`->21x^2-12x=0`

You can write `21=3*7` and `12=3*4`.
You can also factor out one `x`:

`->3*7*x*x-3*4*x=0`
`->3*x*(7x-4)`

So either `x=0`
Or `7x-4=0->7x=4->x=7/4`