Solve 12x + 3 = −81

The solution of 12x + 3 = −81 is x = -7.

12x + 3 = -81\ \Rightarrow\ x = -7

Explain it step by step in chat Make a short video of it

The lines y = 12x + 3 and y = -81 meet at x = -7. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

1
The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.
$12x + 3 = -81$
2
Subtract 3 from both sides:
$12x + 3 - 3 = -81 - 3 \ \Rightarrow\ 12x = -84$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{-84}{12} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$12\cdot(-7) + 3 = -84 + 3 = -81 \checkmark$

LaTeX source of the formulas on this page

\[ 12x + 3 = -81\ \Rightarrow\ x = -7 \]
\[ 12x + 3 = -81 \]
\[ 12x + 3 - 3 = -81 - 3 \ \Rightarrow\ 12x = -84 \]
\[ \frac{12x}{12} = \frac{-84}{12} \ \Rightarrow\ x = -7 \]
\[ 12\cdot(-7) + 3 = -84 + 3 = -81 \checkmark \]

Trying values of x in 12x + 3 = −81

x	12x + 3	Equals -81?
-9	-105	no
-8	-93	no
-7	-81	yes
-6	-69	no
-5	-57	no

Questions

What is x in 12x + 3 = −81?

The solution of 12x + 3 = −81 is x = -7.

How do you solve 12x + 3 = −81?

Subtract 3 from both sides to get 12x = -84, then divide both sides by 12 to get x = -7.

How do I check the answer?

Replace x by -7: 12(-7) + 3 = -81, which is -81.

Solve 12x + 3 = −81

How to work it out

Trying values of x in 12x + 3 = −81

Questions

Similar equations