Solve 3x − 12 = −36

The solution of 3x − 12 = −36 is x = -8.

3x - 12 = -36\ \Rightarrow\ x = -8

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The lines y = 3x − 12 and y = -36 meet at x = -8. 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 subtraction, then the multiplication.
$3x - 12 = -36$
2
Add 12 to both sides:
$3x - 12 + 12 = -36 + 12 \ \Rightarrow\ 3x = -24$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{-24}{3} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$3\cdot(-8) - 12 = -24 - 12 = -36 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 12 = -36\ \Rightarrow\ x = -8 \]
\[ 3x - 12 = -36 \]
\[ 3x - 12 + 12 = -36 + 12 \ \Rightarrow\ 3x = -24 \]
\[ \frac{3x}{3} = \frac{-24}{3} \ \Rightarrow\ x = -8 \]
\[ 3\cdot(-8) - 12 = -24 - 12 = -36 \checkmark \]

Trying values of x in 3x − 12 = −36

x	3x − 12	Equals -36?
-10	-42	no
-9	-39	no
-8	-36	yes
-7	-33	no
-6	-30	no

Questions

What is x in 3x − 12 = −36?

The solution of 3x − 12 = −36 is x = -8.

How do you solve 3x − 12 = −36?

Add 12 to both sides to get 3x = -24, then divide both sides by 3 to get x = -8.

How do I check the answer?

Replace x by -8: 3(-8) − 12 = -36, which is -36.

Solve 3x − 12 = −36

How to work it out

Trying values of x in 3x − 12 = −36

Questions

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