Solve 3x − 3 = 9

The solution of 3x − 3 = 9 is x = 4.

3x - 3 = 9\ \Rightarrow\ x = 4

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

The lines y = 3x − 3 and y = 9 meet at x = 4. 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.
$3x - 3 = 9$
2
Add 3 to both sides:
$3x - 3 + 3 = 9 + 3 \ \Rightarrow\ 3x = 12$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{12}{3} \ \Rightarrow\ x = 4$
4
Check: put x = 4 back into the equation.
$3\cdot4 - 3 = 12 - 3 = 9 \checkmark$

LaTeX source of the formulas on this page

\[ 3x - 3 = 9\ \Rightarrow\ x = 4 \]
\[ 3x - 3 = 9 \]
\[ 3x - 3 + 3 = 9 + 3 \ \Rightarrow\ 3x = 12 \]
\[ \frac{3x}{3} = \frac{12}{3} \ \Rightarrow\ x = 4 \]
\[ 3\cdot4 - 3 = 12 - 3 = 9 \checkmark \]

Trying values of x in 3x − 3 = 9

x	3x − 3	Equals 9?
2	3	no
3	6	no
4	9	yes
5	12	no
6	15	no

Questions

What is x in 3x − 3 = 9?

The solution of 3x − 3 = 9 is x = 4.

How do you solve 3x − 3 = 9?

Add 3 to both sides to get 3x = 12, then divide both sides by 3 to get x = 4.

How do I check the answer?

Replace x by 4: 3(4) − 3 = 9, which is 9.

Solve 3x − 3 = 9

How to work it out

Trying values of x in 3x − 3 = 9

Questions

Similar equations