Solve 12x − 1 = 215

The solution of 12x − 1 = 215 is x = 18.

12x - 1 = 215\ \Rightarrow\ x = 18

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The lines y = 12x − 1 and y = 215 meet at x = 18. 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.
$12x - 1 = 215$
2
Add 1 to both sides:
$12x - 1 + 1 = 215 + 1 \ \Rightarrow\ 12x = 216$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{216}{12} \ \Rightarrow\ x = 18$
4
Check: put x = 18 back into the equation.
$12\cdot18 - 1 = 216 - 1 = 215 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 1 = 215\ \Rightarrow\ x = 18 \]
\[ 12x - 1 = 215 \]
\[ 12x - 1 + 1 = 215 + 1 \ \Rightarrow\ 12x = 216 \]
\[ \frac{12x}{12} = \frac{216}{12} \ \Rightarrow\ x = 18 \]
\[ 12\cdot18 - 1 = 216 - 1 = 215 \checkmark \]

Trying values of x in 12x − 1 = 215

x	12x − 1	Equals 215?
16	191	no
17	203	no
18	215	yes
19	227	no
20	239	no

Questions

What is x in 12x − 1 = 215?

The solution of 12x − 1 = 215 is x = 18.

How do you solve 12x − 1 = 215?

Add 1 to both sides to get 12x = 216, then divide both sides by 12 to get x = 18.

How do I check the answer?

Replace x by 18: 12(18) − 1 = 215, which is 215.

Solve 12x − 1 = 215

How to work it out

Trying values of x in 12x − 1 = 215

Questions

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