Solve 9x + 3 = 138
The solution of 9x + 3 = 138 is x = 15.
How to work it out
- 1
The goal is to get x alone. Undo the operations in the opposite order: first the addition, then the multiplication.
- 2
Subtract 3 from both sides:
- 3
Divide both sides by 9:
- 4
Check: put x = 15 back into the equation.
LaTeX source of the formulas on this page
\[ 9x + 3 = 138\ \Rightarrow\ x = 15 \]
\[ 9x + 3 = 138 \]
\[ 9x + 3 - 3 = 138 - 3 \ \Rightarrow\ 9x = 135 \]
\[ \frac{9x}{9} = \frac{135}{9} \ \Rightarrow\ x = 15 \]
\[ 9\cdot15 + 3 = 135 + 3 = 138 \checkmark \]Trying values of x in 9x + 3 = 138
| x | 9x + 3 | Equals 138? |
|---|---|---|
| 13 | 120 | no |
| 14 | 129 | no |
| 15 | 138 | yes |
| 16 | 147 | no |
| 17 | 156 | no |
Questions
What is x in 9x + 3 = 138?
The solution of 9x + 3 = 138 is x = 15.
How do you solve 9x + 3 = 138?
Subtract 3 from both sides to get 9x = 135, then divide both sides by 9 to get x = 15.
How do I check the answer?
Replace x by 15: 9(15) + 3 = 138, which is 138.