1) 2 + 2 = 5
False
2) √4 = 2
True
3) x + 4 = 8
True for x = 4 and false for any other value of x
4) y^2 = -9
False, since there is no real number whose square is negative
5) |x| = x
True for all positive values of x, but false for negative values of x
6) sin(x) + cos(x) = 1
False for most values of x, but true for x = π/4 and x = 5π/4, as well as any other angle that differs from these by an integer multiple of 2π