Solve 8x − 9 = −1

The solution of 8x − 9 = −1 is x = 1.

8x - 9 = -1\ \Rightarrow\ x = 1

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The lines y = 8x − 9 and y = -1 meet at x = 1. 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.
$8x - 9 = -1$
2
Add 9 to both sides:
$8x - 9 + 9 = -1 + 9 \ \Rightarrow\ 8x = 8$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{8}{8} \ \Rightarrow\ x = 1$
4
Check: put x = 1 back into the equation.
$8\cdot1 - 9 = 8 - 9 = -1 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 9 = -1\ \Rightarrow\ x = 1 \]
\[ 8x - 9 = -1 \]
\[ 8x - 9 + 9 = -1 + 9 \ \Rightarrow\ 8x = 8 \]
\[ \frac{8x}{8} = \frac{8}{8} \ \Rightarrow\ x = 1 \]
\[ 8\cdot1 - 9 = 8 - 9 = -1 \checkmark \]

Trying values of x in 8x − 9 = −1

x	8x − 9	Equals -1?
-1	-17	no
0	-9	no
1	-1	yes
2	7	no
3	15	no

Questions

What is x in 8x − 9 = −1?

The solution of 8x − 9 = −1 is x = 1.

How do you solve 8x − 9 = −1?

Add 9 to both sides to get 8x = 8, then divide both sides by 8 to get x = 1.

How do I check the answer?

Replace x by 1: 8(1) − 9 = -1, which is -1.

Solve 8x − 9 = −1

How to work it out

Trying values of x in 8x − 9 = −1

Questions

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