Homework, but you did make an effort. Does this not show what you need to show?
sqrt(4)
ans =
2
Or this?
sqrt(4) == 2
ans =
logical
1
You were asked to show that statement to be true. Not to solve for the square root. Were you to try to do that, then you should arguably get BOTH branches of the square root. In one line, perhaps this...
solve(str2sym('x^2==4'))
ans =
-2
2
But I will argue that is not what was requested.
