2x^2 + 4x - 6 = 0 Help solve for X using the null theorem

Can you please help me solve 2x^2 + 4x - 6 = 0 using the null theorem, steps included.

2x^2 + 4x - 6 = 0
( 2x - 2 ) ( x + 3 ) = 0
( 2x - 2 ) = 0 ; ( x + 3 ) = 0

( 2x - 2 ) = 0
2x - 2 = 0
2x = 2
2x / 2 = 2 / 2
x = 1

( x + 3 ) = 0
x + 3 = 0
x = - 3

Solutions :
x = 1, - 3

Checking :
( 2x - 2 ) ( x + 3 ) = 0
2x^2 + 6x - 2x - 6 = 0
2x^2 + 4x - 6 = 0

My Answer :
x = 1, - 3

Please define null theorem here. I do not see it online