Solve 6x + 15 = −39

The solution of 6x + 15 = −39 is x = -9.

6x + 15 = -39\ \Rightarrow\ x = -9

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The lines y = 6x + 15 and y = -39 meet at x = -9. 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.
$6x + 15 = -39$
2
Subtract 15 from both sides:
$6x + 15 - 15 = -39 - 15 \ \Rightarrow\ 6x = -54$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{-54}{6} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$6\cdot(-9) + 15 = -54 + 15 = -39 \checkmark$

LaTeX source of the formulas on this page

\[ 6x + 15 = -39\ \Rightarrow\ x = -9 \]
\[ 6x + 15 = -39 \]
\[ 6x + 15 - 15 = -39 - 15 \ \Rightarrow\ 6x = -54 \]
\[ \frac{6x}{6} = \frac{-54}{6} \ \Rightarrow\ x = -9 \]
\[ 6\cdot(-9) + 15 = -54 + 15 = -39 \checkmark \]

Trying values of x in 6x + 15 = −39

x	6x + 15	Equals -39?
-11	-51	no
-10	-45	no
-9	-39	yes
-8	-33	no
-7	-27	no

Questions

What is x in 6x + 15 = −39?

The solution of 6x + 15 = −39 is x = -9.

How do you solve 6x + 15 = −39?

Subtract 15 from both sides to get 6x = -54, then divide both sides by 6 to get x = -9.

How do I check the answer?

Replace x by -9: 6(-9) + 15 = -39, which is -39.

Solve 6x + 15 = −39

How to work it out

Trying values of x in 6x + 15 = −39

Questions

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