Solve 2x − 5 = −21

The solution of 2x − 5 = −21 is x = -8.

2x - 5 = -21\ \Rightarrow\ x = -8

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The lines y = 2x − 5 and y = -21 meet at x = -8. 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.
$2x - 5 = -21$
2
Add 5 to both sides:
$2x - 5 + 5 = -21 + 5 \ \Rightarrow\ 2x = -16$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{-16}{2} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$2\cdot(-8) - 5 = -16 - 5 = -21 \checkmark$

LaTeX source of the formulas on this page

\[ 2x - 5 = -21\ \Rightarrow\ x = -8 \]
\[ 2x - 5 = -21 \]
\[ 2x - 5 + 5 = -21 + 5 \ \Rightarrow\ 2x = -16 \]
\[ \frac{2x}{2} = \frac{-16}{2} \ \Rightarrow\ x = -8 \]
\[ 2\cdot(-8) - 5 = -16 - 5 = -21 \checkmark \]

Trying values of x in 2x − 5 = −21

x	2x − 5	Equals -21?
-10	-25	no
-9	-23	no
-8	-21	yes
-7	-19	no
-6	-17	no

Questions

What is x in 2x − 5 = −21?

The solution of 2x − 5 = −21 is x = -8.

How do you solve 2x − 5 = −21?

Add 5 to both sides to get 2x = -16, then divide both sides by 2 to get x = -8.

How do I check the answer?

Replace x by -8: 2(-8) − 5 = -21, which is -21.

Solve 2x − 5 = −21

How to work it out

Trying values of x in 2x − 5 = −21

Questions

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