Solve 12x − 9 = −57

The solution of 12x − 9 = −57 is x = -4.

12x - 9 = -57\ \Rightarrow\ x = -4

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The lines y = 12x − 9 and y = -57 meet at x = -4. 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.
$12x - 9 = -57$
2
Add 9 to both sides:
$12x - 9 + 9 = -57 + 9 \ \Rightarrow\ 12x = -48$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{-48}{12} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$12\cdot(-4) - 9 = -48 - 9 = -57 \checkmark$

LaTeX source of the formulas on this page

\[ 12x - 9 = -57\ \Rightarrow\ x = -4 \]
\[ 12x - 9 = -57 \]
\[ 12x - 9 + 9 = -57 + 9 \ \Rightarrow\ 12x = -48 \]
\[ \frac{12x}{12} = \frac{-48}{12} \ \Rightarrow\ x = -4 \]
\[ 12\cdot(-4) - 9 = -48 - 9 = -57 \checkmark \]

Trying values of x in 12x − 9 = −57

x	12x − 9	Equals -57?
-6	-81	no
-5	-69	no
-4	-57	yes
-3	-45	no
-2	-33	no

Questions

What is x in 12x − 9 = −57?

The solution of 12x − 9 = −57 is x = -4.

How do you solve 12x − 9 = −57?

Add 9 to both sides to get 12x = -48, then divide both sides by 12 to get x = -4.

How do I check the answer?

Replace x by -4: 12(-4) − 9 = -57, which is -57.

Solve 12x − 9 = −57

How to work it out

Trying values of x in 12x − 9 = −57

Questions

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