A good way to approach this is using the FOIL method.
Multiply first two (F):
[tex]2x * 3x = 6x^2[/tex]
Then outer two (O):
[tex]2x * 4 = 8x[/tex]
Then inner two (I):
[tex]3 * 3x = 9x[/tex]
Then last two (L):
[tex]3 * 4 = 12[/tex]
Add them up:
[tex]6x^2 + 8x + 9x + 12[/tex]
[tex]6x^2 + 17x + 12[/tex]
Hope this helps :)
