Solve 2x − 9 = 9

The solution of 2x − 9 = 9 is x = 9.

2x - 9 = 9\ \Rightarrow\ x = 9

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The lines y = 2x − 9 and y = 9 meet at x = 9. 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.
$2x - 9 = 9$
2
Add 9 to both sides:
$2x - 9 + 9 = 9 + 9 \ \Rightarrow\ 2x = 18$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{18}{2} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$2\cdot9 - 9 = 18 - 9 = 9 \checkmark$

LaTeX source of the formulas on this page

\[ 2x - 9 = 9\ \Rightarrow\ x = 9 \]
\[ 2x - 9 = 9 \]
\[ 2x - 9 + 9 = 9 + 9 \ \Rightarrow\ 2x = 18 \]
\[ \frac{2x}{2} = \frac{18}{2} \ \Rightarrow\ x = 9 \]
\[ 2\cdot9 - 9 = 18 - 9 = 9 \checkmark \]

Trying values of x in 2x − 9 = 9

x	2x − 9	Equals 9?
7	5	no
8	7	no
9	9	yes
10	11	no
11	13	no

Questions

What is x in 2x − 9 = 9?

The solution of 2x − 9 = 9 is x = 9.

How do you solve 2x − 9 = 9?

Add 9 to both sides to get 2x = 18, then divide both sides by 2 to get x = 9.

How do I check the answer?

Replace x by 9: 2(9) − 9 = 9, which is 9.

Solve 2x − 9 = 9

How to work it out

Trying values of x in 2x − 9 = 9

Questions

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