Solve 8x − 1 = 87

The solution of 8x − 1 = 87 is x = 11.

8x - 1 = 87\ \Rightarrow\ x = 11

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

The lines y = 8x − 1 and y = 87 meet at x = 11. 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.
$8x - 1 = 87$
2
Add 1 to both sides:
$8x - 1 + 1 = 87 + 1 \ \Rightarrow\ 8x = 88$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{88}{8} \ \Rightarrow\ x = 11$
4
Check: put x = 11 back into the equation.
$8\cdot11 - 1 = 88 - 1 = 87 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 1 = 87\ \Rightarrow\ x = 11 \]
\[ 8x - 1 = 87 \]
\[ 8x - 1 + 1 = 87 + 1 \ \Rightarrow\ 8x = 88 \]
\[ \frac{8x}{8} = \frac{88}{8} \ \Rightarrow\ x = 11 \]
\[ 8\cdot11 - 1 = 88 - 1 = 87 \checkmark \]

Trying values of x in 8x − 1 = 87

x	8x − 1	Equals 87?
9	71	no
10	79	no
11	87	yes
12	95	no
13	103	no

Questions

What is x in 8x − 1 = 87?

The solution of 8x − 1 = 87 is x = 11.

How do you solve 8x − 1 = 87?

Add 1 to both sides to get 8x = 88, then divide both sides by 8 to get x = 11.

How do I check the answer?

Replace x by 11: 8(11) − 1 = 87, which is 87.

Solve 8x − 1 = 87

How to work it out

Trying values of x in 8x − 1 = 87

Questions

Similar equations