Solve 8x − 4 = 68

The solution of 8x − 4 = 68 is x = 9.

8x - 4 = 68\ \Rightarrow\ x = 9

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The lines y = 8x − 4 and y = 68 meet at x = 9. 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.
$8x - 4 = 68$
2
Add 4 to both sides:
$8x - 4 + 4 = 68 + 4 \ \Rightarrow\ 8x = 72$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{72}{8} \ \Rightarrow\ x = 9$
4
Check: put x = 9 back into the equation.
$8\cdot9 - 4 = 72 - 4 = 68 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 4 = 68\ \Rightarrow\ x = 9 \]
\[ 8x - 4 = 68 \]
\[ 8x - 4 + 4 = 68 + 4 \ \Rightarrow\ 8x = 72 \]
\[ \frac{8x}{8} = \frac{72}{8} \ \Rightarrow\ x = 9 \]
\[ 8\cdot9 - 4 = 72 - 4 = 68 \checkmark \]

Trying values of x in 8x − 4 = 68

x	8x − 4	Equals 68?
7	52	no
8	60	no
9	68	yes
10	76	no
11	84	no

Questions

What is x in 8x − 4 = 68?

The solution of 8x − 4 = 68 is x = 9.

How do you solve 8x − 4 = 68?

Add 4 to both sides to get 8x = 72, then divide both sides by 8 to get x = 9.

How do I check the answer?

Replace x by 9: 8(9) − 4 = 68, which is 68.

Solve 8x − 4 = 68

How to work it out

Trying values of x in 8x − 4 = 68

Questions

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