#### Answer

Distributive property

#### Work Step by Step

The expression shows that multiplying the first term, (x + a), by each of the elements in the second term, x and b, would yield the same result as multiplying the first term by the sum of the elements of the second term. This means the expression is using the distributive property. The distributive property could be used to expand the expression even further:
(x + a) (x + b) = (x + a)x + (x + a)b
(x + a)x + (x + a)b = $x^{2}$ + ax + xb + ab