I need to solve for x for these equations. Also, are any of these if and only if equations based on their solutions?

Code:1) (3 - 2x)(x + 1) = x + 7 - 2(x^2 - 2) 2) 1 / (12 - 4x) = 1 / x^2 - 5x + 6 3) 4 - x = sqrt(x - 2) 4) x(x + 7) = (x + 2)^2 + 3x - 4