Evaluate the expression $\sqrt{6-2\sqrt5} + \sqrt{6+2\sqrt5}$ $$\sqrt{6-2\sqrt5} + \sqrt{6+2\sqrt5}$$
Can anyone tell me the formula to this expression.
I tried to solve in by adding the two expression together and get $\sqrt{12}$ but as I insert each expression separately in calculator the answer is above $\sqrt{12}$.

Set 
$$t=\sqrt{6-2\sqrt5} + \sqrt{6+2\sqrt5}$$
$$t^2=6-2\sqrt5+2\sqrt{(6-2\sqrt5)(6+2\sqrt5)}+6+2\sqrt5$$
$$t^2=12+2\sqrt{36-20}=12+2(4)=20$$
$$t^2=20\implies t=2\sqrt5$$
