Solve 5x + 4 = 39
The solution of 5x + 4 = 39 is x = 7.
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 4 from both sides:
- 3
Divide both sides by 5:
- 4
Check: put x = 7 back into the equation.
LaTeX source of the formulas on this page
\[ 5x + 4 = 39\ \Rightarrow\ x = 7 \]
\[ 5x + 4 = 39 \]
\[ 5x + 4 - 4 = 39 - 4 \ \Rightarrow\ 5x = 35 \]
\[ \frac{5x}{5} = \frac{35}{5} \ \Rightarrow\ x = 7 \]
\[ 5\cdot7 + 4 = 35 + 4 = 39 \checkmark \]Trying values of x in 5x + 4 = 39
| x | 5x + 4 | Equals 39? |
|---|---|---|
| 5 | 29 | no |
| 6 | 34 | no |
| 7 | 39 | yes |
| 8 | 44 | no |
| 9 | 49 | no |
Questions
What is x in 5x + 4 = 39?
The solution of 5x + 4 = 39 is x = 7.
How do you solve 5x + 4 = 39?
Subtract 4 from both sides to get 5x = 35, then divide both sides by 5 to get x = 7.
How do I check the answer?
Replace x by 7: 5(7) + 4 = 39, which is 39.