Solve 11x − 12 = 21

The solution of 11x − 12 = 21 is x = 3.

11x - 12 = 21\ \Rightarrow\ x = 3

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The lines y = 11x − 12 and y = 21 meet at x = 3. 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.
$11x - 12 = 21$
2
Add 12 to both sides:
$11x - 12 + 12 = 21 + 12 \ \Rightarrow\ 11x = 33$
3
Divide both sides by 11:
$\frac{11x}{11} = \frac{33}{11} \ \Rightarrow\ x = 3$
4
Check: put x = 3 back into the equation.
$11\cdot3 - 12 = 33 - 12 = 21 \checkmark$

LaTeX source of the formulas on this page

\[ 11x - 12 = 21\ \Rightarrow\ x = 3 \]
\[ 11x - 12 = 21 \]
\[ 11x - 12 + 12 = 21 + 12 \ \Rightarrow\ 11x = 33 \]
\[ \frac{11x}{11} = \frac{33}{11} \ \Rightarrow\ x = 3 \]
\[ 11\cdot3 - 12 = 33 - 12 = 21 \checkmark \]

Trying values of x in 11x − 12 = 21

x	11x − 12	Equals 21?
1	-1	no
2	10	no
3	21	yes
4	32	no
5	43	no

Questions

What is x in 11x − 12 = 21?

The solution of 11x − 12 = 21 is x = 3.

How do you solve 11x − 12 = 21?

Add 12 to both sides to get 11x = 33, then divide both sides by 11 to get x = 3.

How do I check the answer?

Replace x by 3: 11(3) − 12 = 21, which is 21.

Solve 11x − 12 = 21

How to work it out

Trying values of x in 11x − 12 = 21

Questions

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