(A ∩ B) means "A intersection B". Your problem statement tells you the intersection contains
{3, 4}
Answer: 7 and 8
<u>Step-by-step explanation:</u>
Let x represent the first number, then x + 1 is the other number.
(x)² + (x + 1)² = 113
x² + x² + 2x + 1 = 113 <em>expanded (x + 1)²</em>
2x² + 2x + 1 = 113 <em>added like terms</em>
2x² + 2x - 112 = 0 <em>subtracted 113 from both sides</em>
x² + x - 56 = 0 <em> divided both sides by 2</em>
(x + 8) (x - 7) = 0 <em>factored polynomial</em>
x + 8 = 0 x - 7 = 0 <em>applied zero product property</em>
x = -8 x = 7 <em> solved for x</em>
↓
not valid since the restriction is that x > 0 <em>(a positive number)</em>
So, x = 7 and x + 1 = (7) + 1 = 8
The answer may be 36 but I am not very sure
