Solve 11x − 9 = 123

The solution of 11x − 9 = 123 is x = 12.

11x - 9 = 123\ \Rightarrow\ x = 12

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The lines y = 11x − 9 and y = 123 meet at x = 12. 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.
$11x - 9 = 123$
2
Add 9 to both sides:
$11x - 9 + 9 = 123 + 9 \ \Rightarrow\ 11x = 132$
3
Divide both sides by 11:
$\frac{11x}{11} = \frac{132}{11} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$11\cdot12 - 9 = 132 - 9 = 123 \checkmark$

LaTeX source of the formulas on this page

\[ 11x - 9 = 123\ \Rightarrow\ x = 12 \]
\[ 11x - 9 = 123 \]
\[ 11x - 9 + 9 = 123 + 9 \ \Rightarrow\ 11x = 132 \]
\[ \frac{11x}{11} = \frac{132}{11} \ \Rightarrow\ x = 12 \]
\[ 11\cdot12 - 9 = 132 - 9 = 123 \checkmark \]

Trying values of x in 11x − 9 = 123

x	11x − 9	Equals 123?
10	101	no
11	112	no
12	123	yes
13	134	no
14	145	no

Questions

What is x in 11x − 9 = 123?

The solution of 11x − 9 = 123 is x = 12.

How do you solve 11x − 9 = 123?

Add 9 to both sides to get 11x = 132, then divide both sides by 11 to get x = 12.

How do I check the answer?

Replace x by 12: 11(12) − 9 = 123, which is 123.

Solve 11x − 9 = 123

How to work it out

Trying values of x in 11x − 9 = 123

Questions

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