Solve the following equations: a) x2 − 1 = 0 b) 2x − 4 = 0 c) x − 7 = 0 d) 3x + 6 = 0

Remember to consider both positive and negative roots.

$$x = \pm \sqrt{1}$$ $$x = \pm 1$$

The solutions are $x = 1$ and $x = -1$.

$$\boxed{x = 1, -1}$$

Equation 2:
We need to solve the equation $2x - 4 = 0$.

$$x = \frac{4}{2}$$ $$x = 2$$

The solution is $x = 2$.

$$\boxed{x = 2}$$

Equation 3:
We need to solve the equation $x - 7 = 0$.

$$x = 7$$

The solution is $x = 7$.

$$\boxed{x = 7}$$

Equation 4:
We need to solve the equation $3x + 6 = 0$.

$$x = \frac{-6}{3}$$ $$x = -2$$

The solution is $x = -2$.

$$\boxed{x = -2}$$