Answer:
2
Step-by-step explanation:
[tex](3+\sqrt{7})(3-\sqrt{7}) \\[/tex]
First do 3 x 3 = 9 - keep this 9 to the side for now
Then do 3 x [tex]-\sqrt{7}[/tex] = [tex]-\sqrt{21}[/tex] - also keep this to the side for now
Then do [tex]\sqrt{7}[/tex] x 3 = [tex]\sqrt{21}[/tex]
Then do [tex]-\sqrt{7}[/tex] x [tex]\sqrt{7}[/tex] = -7
So,
9 [tex]-\sqrt{21}[/tex] + [tex]\sqrt{21}[/tex] - 7
Therefore, 9-7 = 2
