Solve 10x − 1 = 79

The solution of 10x − 1 = 79 is x = 8.

10x - 1 = 79\ \Rightarrow\ x = 8

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The lines y = 10x − 1 and y = 79 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.
$10x - 1 = 79$
2
Add 1 to both sides:
$10x - 1 + 1 = 79 + 1 \ \Rightarrow\ 10x = 80$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{80}{10} \ \Rightarrow\ x = 8$
4
Check: put x = 8 back into the equation.
$10\cdot8 - 1 = 80 - 1 = 79 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 1 = 79\ \Rightarrow\ x = 8 \]
\[ 10x - 1 = 79 \]
\[ 10x - 1 + 1 = 79 + 1 \ \Rightarrow\ 10x = 80 \]
\[ \frac{10x}{10} = \frac{80}{10} \ \Rightarrow\ x = 8 \]
\[ 10\cdot8 - 1 = 80 - 1 = 79 \checkmark \]

Trying values of x in 10x − 1 = 79

x	10x − 1	Equals 79?
6	59	no
7	69	no
8	79	yes
9	89	no
10	99	no

Questions

What is x in 10x − 1 = 79?

The solution of 10x − 1 = 79 is x = 8.

How do you solve 10x − 1 = 79?

Add 1 to both sides to get 10x = 80, then divide both sides by 10 to get x = 8.

How do I check the answer?

Replace x by 8: 10(8) − 1 = 79, which is 79.

Solve 10x − 1 = 79

How to work it out

Trying values of x in 10x − 1 = 79

Questions

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