## Calculus with Applications (10th Edition)

$\dfrac{a+1}{2}-\dfrac{a-1}{2}=1$
$\dfrac{a+1}{2}-\dfrac{a-1}{2}$ Since the two rational expressions have the same denominator, evaluate the subtraction of the numerators and use the same denominator in the resulting expression: $\dfrac{a+1}{2}-\dfrac{a-1}{2}=\dfrac{a+1-(a-1)}{2}=...$ Simplify: $...=\dfrac{a+1-a+1}{2}=\dfrac{1+1}{2}=\dfrac{2}{2}=1$