Answer :
[tex] \frac{4 {x}^{2} - 36 }{x + 3} \\ = \frac{4( {x}^{2} - 9)}{x + 3} \\ = \frac{4(x + 3)(x - 3)}{x + 3} \\ = 4(x - 3) \\ = 4x - 12[/tex]
NOTE THE x+3 in the numerator cancels with the x+3 in the denominator.
[tex] \frac{4 {x}^{2} - 36 }{x + 3} \\ = \frac{4( {x}^{2} - 9)}{x + 3} \\ = \frac{4(x + 3)(x - 3)}{x + 3} \\ = 4(x - 3) \\ = 4x - 12[/tex]
NOTE THE x+3 in the numerator cancels with the x+3 in the denominator.