Solve 12x + 6 = −78

The solution of 12x + 6 = −78 is x = -7.

12x + 6 = -78\ \Rightarrow\ x = -7

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The lines y = 12x + 6 and y = -78 meet at x = -7. 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 addition, then the multiplication.
$12x + 6 = -78$
2
Subtract 6 from both sides:
$12x + 6 - 6 = -78 - 6 \ \Rightarrow\ 12x = -84$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{-84}{12} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$12\cdot(-7) + 6 = -84 + 6 = -78 \checkmark$

LaTeX source of the formulas on this page

\[ 12x + 6 = -78\ \Rightarrow\ x = -7 \]
\[ 12x + 6 = -78 \]
\[ 12x + 6 - 6 = -78 - 6 \ \Rightarrow\ 12x = -84 \]
\[ \frac{12x}{12} = \frac{-84}{12} \ \Rightarrow\ x = -7 \]
\[ 12\cdot(-7) + 6 = -84 + 6 = -78 \checkmark \]

Trying values of x in 12x + 6 = −78

x	12x + 6	Equals -78?
-9	-102	no
-8	-90	no
-7	-78	yes
-6	-66	no
-5	-54	no

Questions

What is x in 12x + 6 = −78?

The solution of 12x + 6 = −78 is x = -7.

How do you solve 12x + 6 = −78?

Subtract 6 from both sides to get 12x = -84, then divide both sides by 12 to get x = -7.

How do I check the answer?

Replace x by -7: 12(-7) + 6 = -78, which is -78.

Solve 12x + 6 = −78

How to work it out

Trying values of x in 12x + 6 = −78

Questions

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