Solve 3x − 12 = −18

The solution of 3x − 12 = −18 is x = -2.

3x - 12 = -18\ \Rightarrow\ x = -2

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The lines y = 3x − 12 and y = -18 meet at x = -2. 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.
$3x - 12 = -18$
2
Add 12 to both sides:
$3x - 12 + 12 = -18 + 12 \ \Rightarrow\ 3x = -6$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{-6}{3} \ \Rightarrow\ x = -2$
4
Check: put x = -2 back into the equation.
$3\cdot(-2) - 12 = -6 - 12 = -18 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 12 = -18\ \Rightarrow\ x = -2 \]
\[ 3x - 12 = -18 \]
\[ 3x - 12 + 12 = -18 + 12 \ \Rightarrow\ 3x = -6 \]
\[ \frac{3x}{3} = \frac{-6}{3} \ \Rightarrow\ x = -2 \]
\[ 3\cdot(-2) - 12 = -6 - 12 = -18 \checkmark \]

Trying values of x in 3x − 12 = −18

x	3x − 12	Equals -18?
-4	-24	no
-3	-21	no
-2	-18	yes
-1	-15	no
0	-12	no

Questions

What is x in 3x − 12 = −18?

The solution of 3x − 12 = −18 is x = -2.

How do you solve 3x − 12 = −18?

Add 12 to both sides to get 3x = -6, then divide both sides by 3 to get x = -2.

How do I check the answer?

Replace x by -2: 3(-2) − 12 = -18, which is -18.

Solve 3x − 12 = −18

How to work it out

Trying values of x in 3x − 12 = −18

Questions

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