Answer
$(r-6)(r-7)$
Work Step by Step
List the pairs of numbers whose product is 42.
1,42
2,21
3,14
6,7
Determine which pair sums to 13, Since -13 is the coefficient of r and 42 is positive, both expressions of the binomial will be subtraction.
$6+7=13$
$r^2-13r+42=(r-6)(r-7)$
