Solve 3x − 12 = 3

The solution of 3x − 12 = 3 is x = 5.

3x - 12 = 3\ \Rightarrow\ x = 5

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The lines y = 3x − 12 and y = 3 meet at x = 5. 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.
$3x - 12 = 3$
2
Add 12 to both sides:
$3x - 12 + 12 = 3 + 12 \ \Rightarrow\ 3x = 15$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{15}{3} \ \Rightarrow\ x = 5$
4
Check: put x = 5 back into the equation.
$3\cdot5 - 12 = 15 - 12 = 3 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 12 = 3\ \Rightarrow\ x = 5 \]
\[ 3x - 12 = 3 \]
\[ 3x - 12 + 12 = 3 + 12 \ \Rightarrow\ 3x = 15 \]
\[ \frac{3x}{3} = \frac{15}{3} \ \Rightarrow\ x = 5 \]
\[ 3\cdot5 - 12 = 15 - 12 = 3 \checkmark \]

Trying values of x in 3x − 12 = 3

x	3x − 12	Equals 3?
3	-3	no
4	0	no
5	3	yes
6	6	no
7	9	no

Questions

What is x in 3x − 12 = 3?

The solution of 3x − 12 = 3 is x = 5.

How do you solve 3x − 12 = 3?

Add 12 to both sides to get 3x = 15, then divide both sides by 3 to get x = 5.

How do I check the answer?

Replace x by 5: 3(5) − 12 = 3, which is 3.

Solve 3x − 12 = 3

How to work it out

Trying values of x in 3x − 12 = 3

Questions

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