Solve 8x − 1 = −9

The solution of 8x − 1 = −9 is x = -1.

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

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

LaTeX source of the formulas on this page

\[ 8x - 1 = -9\ \Rightarrow\ x = -1 \]
\[ 8x - 1 = -9 \]
\[ 8x - 1 + 1 = -9 + 1 \ \Rightarrow\ 8x = -8 \]
\[ \frac{8x}{8} = \frac{-8}{8} \ \Rightarrow\ x = -1 \]
\[ 8\cdot(-1) - 1 = -8 - 1 = -9 \checkmark \]

Trying values of x in 8x − 1 = −9

x	8x − 1	Equals -9?
-3	-25	no
-2	-17	no
-1	-9	yes
0	-1	no
1	7	no

Questions

What is x in 8x − 1 = −9?

The solution of 8x − 1 = −9 is x = -1.

How do you solve 8x − 1 = −9?

Add 1 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) − 1 = -9, which is -9.

Solve 8x − 1 = −9

How to work it out

Trying values of x in 8x − 1 = −9

Questions

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