Solve 9x − 12 = 51

The solution of 9x − 12 = 51 is x = 7.

9x - 12 = 51\ \Rightarrow\ x = 7

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The lines y = 9x − 12 and y = 51 meet at x = 7. 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.
$9x - 12 = 51$
2
Add 12 to both sides:
$9x - 12 + 12 = 51 + 12 \ \Rightarrow\ 9x = 63$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{63}{9} \ \Rightarrow\ x = 7$
4
Check: put x = 7 back into the equation.
$9\cdot7 - 12 = 63 - 12 = 51 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 12 = 51\ \Rightarrow\ x = 7 \]
\[ 9x - 12 = 51 \]
\[ 9x - 12 + 12 = 51 + 12 \ \Rightarrow\ 9x = 63 \]
\[ \frac{9x}{9} = \frac{63}{9} \ \Rightarrow\ x = 7 \]
\[ 9\cdot7 - 12 = 63 - 12 = 51 \checkmark \]

Trying values of x in 9x − 12 = 51

x	9x − 12	Equals 51?
5	33	no
6	42	no
7	51	yes
8	60	no
9	69	no

Questions

What is x in 9x − 12 = 51?

The solution of 9x − 12 = 51 is x = 7.

How do you solve 9x − 12 = 51?

Add 12 to both sides to get 9x = 63, then divide both sides by 9 to get x = 7.

How do I check the answer?

Replace x by 7: 9(7) − 12 = 51, which is 51.

Solve 9x − 12 = 51

How to work it out

Trying values of x in 9x − 12 = 51

Questions

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