Question

Simplify the following expressions.
$(\sqrt{11}-\sqrt{7})(\sqrt{11}+\sqrt{7})$

Answer 1

$(\sqrt{11}-\sqrt{7})(\sqrt{11}+\sqrt{7})$

$=\sqrt{11}\times \sqrt{11}-\sqrt{7}\times \sqrt{11}+\sqrt{7}\times \sqrt{11}+\sqrt{7}\times -\sqrt{11}$

$=11-\sqrt{77}+\sqrt{77}-7$

$=11-7=4$