Solve 9x − 1 = −91

The solution of 9x − 1 = −91 is x = -10.

9x - 1 = -91\ \Rightarrow\ x = -10

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The lines y = 9x − 1 and y = -91 meet at x = -10. 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.
$9x - 1 = -91$
2
Add 1 to both sides:
$9x - 1 + 1 = -91 + 1 \ \Rightarrow\ 9x = -90$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{-90}{9} \ \Rightarrow\ x = -10$
4
Check: put x = -10 back into the equation.
$9\cdot(-10) - 1 = -90 - 1 = -91 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 1 = -91\ \Rightarrow\ x = -10 \]
\[ 9x - 1 = -91 \]
\[ 9x - 1 + 1 = -91 + 1 \ \Rightarrow\ 9x = -90 \]
\[ \frac{9x}{9} = \frac{-90}{9} \ \Rightarrow\ x = -10 \]
\[ 9\cdot(-10) - 1 = -90 - 1 = -91 \checkmark \]

Trying values of x in 9x − 1 = −91

x	9x − 1	Equals -91?
-12	-109	no
-11	-100	no
-10	-91	yes
-9	-82	no
-8	-73	no

Questions

What is x in 9x − 1 = −91?

The solution of 9x − 1 = −91 is x = -10.

How do you solve 9x − 1 = −91?

Add 1 to both sides to get 9x = -90, then divide both sides by 9 to get x = -10.

How do I check the answer?

Replace x by -10: 9(-10) − 1 = -91, which is -91.

Solve 9x − 1 = −91

How to work it out

Trying values of x in 9x − 1 = −91

Questions

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