Solve 8x − 1 = 39

The solution of 8x − 1 = 39 is x = 5.

8x - 1 = 39\ \Rightarrow\ x = 5

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The lines y = 8x − 1 and y = 39 meet at x = 5. 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.
$8x - 1 = 39$
2
Add 1 to both sides:
$8x - 1 + 1 = 39 + 1 \ \Rightarrow\ 8x = 40$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{40}{8} \ \Rightarrow\ x = 5$
4
Check: put x = 5 back into the equation.
$8\cdot5 - 1 = 40 - 1 = 39 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 1 = 39\ \Rightarrow\ x = 5 \]
\[ 8x - 1 = 39 \]
\[ 8x - 1 + 1 = 39 + 1 \ \Rightarrow\ 8x = 40 \]
\[ \frac{8x}{8} = \frac{40}{8} \ \Rightarrow\ x = 5 \]
\[ 8\cdot5 - 1 = 40 - 1 = 39 \checkmark \]

Trying values of x in 8x − 1 = 39

x	8x − 1	Equals 39?
3	23	no
4	31	no
5	39	yes
6	47	no
7	55	no

Questions

What is x in 8x − 1 = 39?

The solution of 8x − 1 = 39 is x = 5.

How do you solve 8x − 1 = 39?

Add 1 to both sides to get 8x = 40, then divide both sides by 8 to get x = 5.

How do I check the answer?

Replace x by 5: 8(5) − 1 = 39, which is 39.

Solve 8x − 1 = 39

How to work it out

Trying values of x in 8x − 1 = 39

Questions

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