Solve 10x − 1 = −21

The solution of 10x − 1 = −21 is x = -2.

10x - 1 = -21\ \Rightarrow\ x = -2

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The lines y = 10x − 1 and y = -21 meet at x = -2. 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.
$10x - 1 = -21$
2
Add 1 to both sides:
$10x - 1 + 1 = -21 + 1 \ \Rightarrow\ 10x = -20$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-20}{10} \ \Rightarrow\ x = -2$
4
Check: put x = -2 back into the equation.
$10\cdot(-2) - 1 = -20 - 1 = -21 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 1 = -21\ \Rightarrow\ x = -2 \]
\[ 10x - 1 = -21 \]
\[ 10x - 1 + 1 = -21 + 1 \ \Rightarrow\ 10x = -20 \]
\[ \frac{10x}{10} = \frac{-20}{10} \ \Rightarrow\ x = -2 \]
\[ 10\cdot(-2) - 1 = -20 - 1 = -21 \checkmark \]

Trying values of x in 10x − 1 = −21

x	10x − 1	Equals -21?
-4	-41	no
-3	-31	no
-2	-21	yes
-1	-11	no
0	-1	no

Questions

What is x in 10x − 1 = −21?

The solution of 10x − 1 = −21 is x = -2.

How do you solve 10x − 1 = −21?

Add 1 to both sides to get 10x = -20, then divide both sides by 10 to get x = -2.

How do I check the answer?

Replace x by -2: 10(-2) − 1 = -21, which is -21.

Solve 10x − 1 = −21

How to work it out

Trying values of x in 10x − 1 = −21

Questions

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