Solve 12x − 8 = −128

The solution of 12x − 8 = −128 is x = -10.

12x - 8 = -128\ \Rightarrow\ x = -10

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The lines y = 12x − 8 and y = -128 meet at x = -10. 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.
$12x - 8 = -128$
2
Add 8 to both sides:
$12x - 8 + 8 = -128 + 8 \ \Rightarrow\ 12x = -120$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{-120}{12} \ \Rightarrow\ x = -10$
4
Check: put x = -10 back into the equation.
$12\cdot(-10) - 8 = -120 - 8 = -128 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 8 = -128\ \Rightarrow\ x = -10 \]
\[ 12x - 8 = -128 \]
\[ 12x - 8 + 8 = -128 + 8 \ \Rightarrow\ 12x = -120 \]
\[ \frac{12x}{12} = \frac{-120}{12} \ \Rightarrow\ x = -10 \]
\[ 12\cdot(-10) - 8 = -120 - 8 = -128 \checkmark \]

Trying values of x in 12x − 8 = −128

x	12x − 8	Equals -128?
-12	-152	no
-11	-140	no
-10	-128	yes
-9	-116	no
-8	-104	no

Questions

What is x in 12x − 8 = −128?

The solution of 12x − 8 = −128 is x = -10.

How do you solve 12x − 8 = −128?

Add 8 to both sides to get 12x = -120, then divide both sides by 12 to get x = -10.

How do I check the answer?

Replace x by -10: 12(-10) − 8 = -128, which is -128.

Solve 12x − 8 = −128

How to work it out

Trying values of x in 12x − 8 = −128

Questions

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