Solve 2x − 9 = −1

The solution of 2x − 9 = −1 is x = 4.

2x - 9 = -1\ \Rightarrow\ x = 4

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The lines y = 2x − 9 and y = -1 meet at x = 4. 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.
$2x - 9 = -1$
2
Add 9 to both sides:
$2x - 9 + 9 = -1 + 9 \ \Rightarrow\ 2x = 8$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{8}{2} \ \Rightarrow\ x = 4$
4
Check: put x = 4 back into the equation.
$2\cdot4 - 9 = 8 - 9 = -1 \checkmark$

LaTeX source of the formulas on this page

\[ 2x - 9 = -1\ \Rightarrow\ x = 4 \]
\[ 2x - 9 = -1 \]
\[ 2x - 9 + 9 = -1 + 9 \ \Rightarrow\ 2x = 8 \]
\[ \frac{2x}{2} = \frac{8}{2} \ \Rightarrow\ x = 4 \]
\[ 2\cdot4 - 9 = 8 - 9 = -1 \checkmark \]

Trying values of x in 2x − 9 = −1

x	2x − 9	Equals -1?
2	-5	no
3	-3	no
4	-1	yes
5	1	no
6	3	no

Questions

What is x in 2x − 9 = −1?

The solution of 2x − 9 = −1 is x = 4.

How do you solve 2x − 9 = −1?

Add 9 to both sides to get 2x = 8, then divide both sides by 2 to get x = 4.

How do I check the answer?

Replace x by 4: 2(4) − 9 = -1, which is -1.

Solve 2x − 9 = −1

How to work it out

Trying values of x in 2x − 9 = −1

Questions

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