Solve 3x − 15 = −12

The solution of 3x − 15 = −12 is x = 1.

3x - 15 = -12\ \Rightarrow\ x = 1

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

The lines y = 3x − 15 and y = -12 meet at x = 1. 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.
$3x - 15 = -12$
2
Add 15 to both sides:
$3x - 15 + 15 = -12 + 15 \ \Rightarrow\ 3x = 3$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{3}{3} \ \Rightarrow\ x = 1$
4
Check: put x = 1 back into the equation.
$3\cdot1 - 15 = 3 - 15 = -12 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 15 = -12\ \Rightarrow\ x = 1 \]
\[ 3x - 15 = -12 \]
\[ 3x - 15 + 15 = -12 + 15 \ \Rightarrow\ 3x = 3 \]
\[ \frac{3x}{3} = \frac{3}{3} \ \Rightarrow\ x = 1 \]
\[ 3\cdot1 - 15 = 3 - 15 = -12 \checkmark \]

Trying values of x in 3x − 15 = −12

x	3x − 15	Equals -12?
-1	-18	no
0	-15	no
1	-12	yes
2	-9	no
3	-6	no

Questions

What is x in 3x − 15 = −12?

The solution of 3x − 15 = −12 is x = 1.

How do you solve 3x − 15 = −12?

Add 15 to both sides to get 3x = 3, then divide both sides by 3 to get x = 1.

How do I check the answer?

Replace x by 1: 3(1) − 15 = -12, which is -12.

Solve 3x − 15 = −12

How to work it out

Trying values of x in 3x − 15 = −12

Questions

Similar equations