To simplify the expression \((5 + \sqrt{65})(5 + \sqrt{143})\), we can use the distributive property (also known as the FOIL method for binomials).
First, we expand the expression:
\[ (5 + \sqrt{65})(5 + \sqrt{143}) = 5 \times 5 + 5 \times \sqrt{143} + \sqrt{65} \times 5 + \sqrt{65} \times \sqrt{143} \]
This can be simplified as follows:
- \(5 \times 5 = 25\)
- \(5 \times \sqrt{143} = 5\sqrt{143}\)
- \(\sqrt{65} \times 5 = 5\sqrt{65}\)
- \(\sqrt{65} \times \sqrt{143} = \sqrt{65 \times 143}\)
Now, calculate \(65 \times 143\):
\[ 65 \times 143 = 9295 \]
Thus, \(\sqrt{65 \times 143} = \sqrt{9295}\).
Putting it all together, we have:
\[ (5 + \sqrt{65})(5 + \sqrt{143}) = 25 + 5\sqrt{143} + 5\sqrt{65} + \sqrt{9295} \]
So the final answer is:
\[ 25 + 5\sqrt{143} + 5\sqrt{65} + \sqrt{9295} \]