Solve 4x − 8 = −20

The solution of 4x − 8 = −20 is x = -3.

4x - 8 = -20\ \Rightarrow\ x = -3

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The lines y = 4x − 8 and y = -20 meet at x = -3. 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.
$4x - 8 = -20$
2
Add 8 to both sides:
$4x - 8 + 8 = -20 + 8 \ \Rightarrow\ 4x = -12$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-12}{4} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$4\cdot(-3) - 8 = -12 - 8 = -20 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 8 = -20\ \Rightarrow\ x = -3 \]
\[ 4x - 8 = -20 \]
\[ 4x - 8 + 8 = -20 + 8 \ \Rightarrow\ 4x = -12 \]
\[ \frac{4x}{4} = \frac{-12}{4} \ \Rightarrow\ x = -3 \]
\[ 4\cdot(-3) - 8 = -12 - 8 = -20 \checkmark \]

Trying values of x in 4x − 8 = −20

x	4x − 8	Equals -20?
-5	-28	no
-4	-24	no
-3	-20	yes
-2	-16	no
-1	-12	no

Questions

What is x in 4x − 8 = −20?

The solution of 4x − 8 = −20 is x = -3.

How do you solve 4x − 8 = −20?

Add 8 to both sides to get 4x = -12, then divide both sides by 4 to get x = -3.

How do I check the answer?

Replace x by -3: 4(-3) − 8 = -20, which is -20.

Solve 4x − 8 = −20

How to work it out

Trying values of x in 4x − 8 = −20

Questions

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