Answer and explanation:
[tex]x^{2} + 13x + 42[/tex]
(x + 6)(x + 7)
List the multiples of 42
42: 1 2 3 6 7 14 21 42
Then see which of the multiples add up to 13
1 x 42 = 42 --> 1 + 42 [tex]\neq[/tex] 13
2 x 21 = 42 --> 2 + 21 [tex]\neq[/tex] 13
3 x 14 = 42 --> 3 + 14 [tex]\neq[/tex] 13
6 x 7 = 42 --> 6 + 7 = 13