Solve 4x − 1 = 39

The solution of 4x − 1 = 39 is x = 10.

4x - 1 = 39\ \Rightarrow\ x = 10

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The lines y = 4x − 1 and y = 39 meet at x = 10. 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.
$4x - 1 = 39$
2
Add 1 to both sides:
$4x - 1 + 1 = 39 + 1 \ \Rightarrow\ 4x = 40$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{40}{4} \ \Rightarrow\ x = 10$
4
Check: put x = 10 back into the equation.
$4\cdot10 - 1 = 40 - 1 = 39 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 1 = 39\ \Rightarrow\ x = 10 \]
\[ 4x - 1 = 39 \]
\[ 4x - 1 + 1 = 39 + 1 \ \Rightarrow\ 4x = 40 \]
\[ \frac{4x}{4} = \frac{40}{4} \ \Rightarrow\ x = 10 \]
\[ 4\cdot10 - 1 = 40 - 1 = 39 \checkmark \]

Trying values of x in 4x − 1 = 39

x	4x − 1	Equals 39?
8	31	no
9	35	no
10	39	yes
11	43	no
12	47	no

Questions

What is x in 4x − 1 = 39?

The solution of 4x − 1 = 39 is x = 10.

How do you solve 4x − 1 = 39?

Add 1 to both sides to get 4x = 40, then divide both sides by 4 to get x = 10.

How do I check the answer?

Replace x by 10: 4(10) − 1 = 39, which is 39.

Solve 4x − 1 = 39

How to work it out

Trying values of x in 4x − 1 = 39

Questions

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