Final answer:
The expression in factored form is (x+6)(x+7).
Step-by-step explanation:
To factor the expression x^2 +13x+42, we need to find two binomials that, when multiplied together, will give us the original quadratic expression. We are looking for two numbers whose product is equal to 42 and whose sum is equal to 13. These numbers are 6 and 7. Therefore, the expression in factored form is (x+6)(x+7).