Solve 3x ā 5 = ā20
The solution of 3x ā 5 = ā20 is x = -5.
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.
- 2
Add 5 to both sides:
- 3
Divide both sides by 3:
- 4
Check: put x = -5 back into the equation.
LaTeX source of the formulas on this page
\[ 3x - 5 = -20\ \Rightarrow\ x = -5 \]
\[ 3x - 5 = -20 \]
\[ 3x - 5 + 5 = -20 + 5 \ \Rightarrow\ 3x = -15 \]
\[ \frac{3x}{3} = \frac{-15}{3} \ \Rightarrow\ x = -5 \]
\[ 3\cdot(-5) - 5 = -15 - 5 = -20 \checkmark \]Trying values of x in 3x ā 5 = ā20
| x | 3x ā 5 | Equals -20? |
|---|---|---|
| -7 | -26 | no |
| -6 | -23 | no |
| -5 | -20 | yes |
| -4 | -17 | no |
| -3 | -14 | no |
Questions
What is x in 3x ā 5 = ā20?
The solution of 3x ā 5 = ā20 is x = -5.
How do you solve 3x ā 5 = ā20?
Add 5 to both sides to get 3x = -15, then divide both sides by 3 to get x = -5.
How do I check the answer?
Replace x by -5: 3(-5) ā 5 = -20, which is -20.