Solve 7x − 1 = 125

The solution of 7x − 1 = 125 is x = 18.

7x - 1 = 125\ \Rightarrow\ x = 18

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The lines y = 7x − 1 and y = 125 meet at x = 18. 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.
$7x - 1 = 125$
2
Add 1 to both sides:
$7x - 1 + 1 = 125 + 1 \ \Rightarrow\ 7x = 126$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{126}{7} \ \Rightarrow\ x = 18$
4
Check: put x = 18 back into the equation.
$7\cdot18 - 1 = 126 - 1 = 125 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 1 = 125\ \Rightarrow\ x = 18 \]
\[ 7x - 1 = 125 \]
\[ 7x - 1 + 1 = 125 + 1 \ \Rightarrow\ 7x = 126 \]
\[ \frac{7x}{7} = \frac{126}{7} \ \Rightarrow\ x = 18 \]
\[ 7\cdot18 - 1 = 126 - 1 = 125 \checkmark \]

Trying values of x in 7x − 1 = 125

x	7x − 1	Equals 125?
16	111	no
17	118	no
18	125	yes
19	132	no
20	139	no

Questions

What is x in 7x − 1 = 125?

The solution of 7x − 1 = 125 is x = 18.

How do you solve 7x − 1 = 125?

Add 1 to both sides to get 7x = 126, then divide both sides by 7 to get x = 18.

How do I check the answer?

Replace x by 18: 7(18) − 1 = 125, which is 125.

Solve 7x − 1 = 125

How to work it out

Trying values of x in 7x − 1 = 125

Questions

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