Solve 4x − 8 = 64

The solution of 4x − 8 = 64 is x = 18.

4x - 8 = 64\ \Rightarrow\ x = 18

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The lines y = 4x − 8 and y = 64 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.
$4x - 8 = 64$
2
Add 8 to both sides:
$4x - 8 + 8 = 64 + 8 \ \Rightarrow\ 4x = 72$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{72}{4} \ \Rightarrow\ x = 18$
4
Check: put x = 18 back into the equation.
$4\cdot18 - 8 = 72 - 8 = 64 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 8 = 64\ \Rightarrow\ x = 18 \]
\[ 4x - 8 = 64 \]
\[ 4x - 8 + 8 = 64 + 8 \ \Rightarrow\ 4x = 72 \]
\[ \frac{4x}{4} = \frac{72}{4} \ \Rightarrow\ x = 18 \]
\[ 4\cdot18 - 8 = 72 - 8 = 64 \checkmark \]

Trying values of x in 4x − 8 = 64

x	4x − 8	Equals 64?
16	56	no
17	60	no
18	64	yes
19	68	no
20	72	no

Questions

What is x in 4x − 8 = 64?

The solution of 4x − 8 = 64 is x = 18.

How do you solve 4x − 8 = 64?

Add 8 to both sides to get 4x = 72, then divide both sides by 4 to get x = 18.

How do I check the answer?

Replace x by 18: 4(18) − 8 = 64, which is 64.

Solve 4x − 8 = 64

How to work it out

Trying values of x in 4x − 8 = 64

Questions

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