Solve 5x − 1 = −21

The solution of 5x − 1 = −21 is x = -4.

5x - 1 = -21\ \Rightarrow\ x = -4

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The lines y = 5x − 1 and y = -21 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.
$5x - 1 = -21$
2
Add 1 to both sides:
$5x - 1 + 1 = -21 + 1 \ \Rightarrow\ 5x = -20$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-20}{5} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$5\cdot(-4) - 1 = -20 - 1 = -21 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 1 = -21\ \Rightarrow\ x = -4 \]
\[ 5x - 1 = -21 \]
\[ 5x - 1 + 1 = -21 + 1 \ \Rightarrow\ 5x = -20 \]
\[ \frac{5x}{5} = \frac{-20}{5} \ \Rightarrow\ x = -4 \]
\[ 5\cdot(-4) - 1 = -20 - 1 = -21 \checkmark \]

Trying values of x in 5x − 1 = −21

x	5x − 1	Equals -21?
-6	-31	no
-5	-26	no
-4	-21	yes
-3	-16	no
-2	-11	no

Questions

What is x in 5x − 1 = −21?

The solution of 5x − 1 = −21 is x = -4.

How do you solve 5x − 1 = −21?

Add 1 to both sides to get 5x = -20, then divide both sides by 5 to get x = -4.

How do I check the answer?

Replace x by -4: 5(-4) − 1 = -21, which is -21.

Solve 5x − 1 = −21

How to work it out

Trying values of x in 5x − 1 = −21

Questions

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