I don’t know the answer

Answer:
(a+b) (a-b) =a^2 - b^2
In this question a=2, b=square root of 5
So 2*2=4 square root of 5 times square root of 5 is 5
4-5=-1
Answer:
I believe the answer is -1.
Step-by-step explanation:
So I distributed,
2 x 2 = 4
[tex]-\sqrt{5}[/tex] x 2 = [tex]-2\sqrt{5}[/tex]
[tex]\sqrt{5}[/tex] x 2 = [tex]2\sqrt{5}[/tex]
[tex]\sqrt{5}[/tex] x [tex]-\sqrt{5}[/tex] = -5
4 [tex]-2\sqrt{5}[/tex] + [tex]2\sqrt{5}[/tex] - 5 = ?
the radicals cancel out and 4 -5 = -1