Solve 2x + 4 = 20
The solution of 2x + 4 = 20 is x = 8.
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 2:
- 4
Check: put x = 8 back into the equation.
LaTeX source of the formulas on this page
\[ 2x + 4 = 20\ \Rightarrow\ x = 8 \]
\[ 2x + 4 = 20 \]
\[ 2x + 4 - 4 = 20 - 4 \ \Rightarrow\ 2x = 16 \]
\[ \frac{2x}{2} = \frac{16}{2} \ \Rightarrow\ x = 8 \]
\[ 2\cdot8 + 4 = 16 + 4 = 20 \checkmark \]Trying values of x in 2x + 4 = 20
| x | 2x + 4 | Equals 20? |
|---|---|---|
| 6 | 16 | no |
| 7 | 18 | no |
| 8 | 20 | yes |
| 9 | 22 | no |
| 10 | 24 | no |
Questions
What is x in 2x + 4 = 20?
The solution of 2x + 4 = 20 is x = 8.
How do you solve 2x + 4 = 20?
Subtract 4 from both sides to get 2x = 16, then divide both sides by 2 to get x = 8.
How do I check the answer?
Replace x by 8: 2(8) + 4 = 20, which is 20.