Question

Find the product of (5-√7) and (5+√7)

Answer 1

We are to evaluate the expression:

$(5-\sqrt{7})(5+\sqrt{7})$

First, we write it in the form below:

$5(5+\sqrt{7})-\sqrt{7}(5+\sqrt{7})$

Next. we open the brackets

$\begin{gathered} =25+5\sqrt{7}-5\sqrt{7}-(\sqrt{7})^2 \\ =25-7 \\ =18 \end{gathered}$

Therefore, the product of the two terms is 18.