Solve 2x + 7 = 31

The solution of 2x + 7 = 31 is x = 12.

2x + 7 = 31\ \Rightarrow\ x = 12

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The lines y = 2x + 7 and y = 31 meet at x = 12. 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 addition, then the multiplication.
$2x + 7 = 31$
2
Subtract 7 from both sides:
$2x + 7 - 7 = 31 - 7 \ \Rightarrow\ 2x = 24$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{24}{2} \ \Rightarrow\ x = 12$
4
Check: put x = 12 back into the equation.
$2\cdot12 + 7 = 24 + 7 = 31 \checkmark$

LaTeX source of the formulas on this page

\[ 2x + 7 = 31\ \Rightarrow\ x = 12 \]
\[ 2x + 7 = 31 \]
\[ 2x + 7 - 7 = 31 - 7 \ \Rightarrow\ 2x = 24 \]
\[ \frac{2x}{2} = \frac{24}{2} \ \Rightarrow\ x = 12 \]
\[ 2\cdot12 + 7 = 24 + 7 = 31 \checkmark \]

Trying values of x in 2x + 7 = 31

x	2x + 7	Equals 31?
10	27	no
11	29	no
12	31	yes
13	33	no
14	35	no

Questions

What is x in 2x + 7 = 31?

The solution of 2x + 7 = 31 is x = 12.

How do you solve 2x + 7 = 31?

Subtract 7 from both sides to get 2x = 24, then divide both sides by 2 to get x = 12.

How do I check the answer?

Replace x by 12: 2(12) + 7 = 31, which is 31.

Solve 2x + 7 = 31

How to work it out

Trying values of x in 2x + 7 = 31

Questions

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