# How about 4, 5, 6?

**Number Theory**Level 4

\[\sqrt { ab+56 } -\sqrt { ab-56 } =4\]

If all the \(n\) pairs of positive integers \((a,b) \) that satisfy the equation above are

\[ (a_1 ,b_1) , (a_2, b_2) , \ldots , (a_n, b_n) ,\]

submit your answer as \(\displaystyle \sum _{ i=1 }^{ n }{ a_{ i }b_{ i } } \).