Question

Solve using the addition principle. Don’t forget to perform a check. -9+x=-12The solution is x = __

Answer 1

Using the addition principle which states that:

`\text{If a = b, then a+c=b+c}`

In our case, we add 9 to both sides to get:

`\begin{gathered} -9+x=-12 \\ -9+x+9=-12+9 \\ x=-3 \end{gathered}`

Performing our check,

`\begin{gathered} -9+x=-12 \\ -9+(-3)=-9-3=-12 \end{gathered}`

Therefore, x = -3