Solve 4x − 1 = 31

The solution of 4x − 1 = 31 is x = 8.

4x - 1 = 31\ \Rightarrow\ x = 8

Explain it step by step in chat Make a short video of it

The lines y = 4x − 1 and y = 31 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.
$4x - 1 = 31$
2
Add 1 to both sides:
$4x - 1 + 1 = 31 + 1 \ \Rightarrow\ 4x = 32$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{32}{4} \ \Rightarrow\ x = 8$
4
Check: put x = 8 back into the equation.
$4\cdot8 - 1 = 32 - 1 = 31 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 1 = 31\ \Rightarrow\ x = 8 \]
\[ 4x - 1 = 31 \]
\[ 4x - 1 + 1 = 31 + 1 \ \Rightarrow\ 4x = 32 \]
\[ \frac{4x}{4} = \frac{32}{4} \ \Rightarrow\ x = 8 \]
\[ 4\cdot8 - 1 = 32 - 1 = 31 \checkmark \]

Trying values of x in 4x − 1 = 31

x	4x − 1	Equals 31?
6	23	no
7	27	no
8	31	yes
9	35	no
10	39	no

Questions

What is x in 4x − 1 = 31?

The solution of 4x − 1 = 31 is x = 8.

How do you solve 4x − 1 = 31?

Add 1 to both sides to get 4x = 32, then divide both sides by 4 to get x = 8.

How do I check the answer?

Replace x by 8: 4(8) − 1 = 31, which is 31.

Solve 4x − 1 = 31

How to work it out

Trying values of x in 4x − 1 = 31

Questions

Similar equations