Solve 6x + 9 = −15

The solution of 6x + 9 = −15 is x = -4.

6x + 9 = -15\ \Rightarrow\ x = -4

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The lines y = 6x + 9 and y = -15 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 addition, then the multiplication.
$6x + 9 = -15$
2
Subtract 9 from both sides:
$6x + 9 - 9 = -15 - 9 \ \Rightarrow\ 6x = -24$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{-24}{6} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$6\cdot(-4) + 9 = -24 + 9 = -15 \checkmark$

LaTeX source of the formulas on this page

\[ 6x + 9 = -15\ \Rightarrow\ x = -4 \]
\[ 6x + 9 = -15 \]
\[ 6x + 9 - 9 = -15 - 9 \ \Rightarrow\ 6x = -24 \]
\[ \frac{6x}{6} = \frac{-24}{6} \ \Rightarrow\ x = -4 \]
\[ 6\cdot(-4) + 9 = -24 + 9 = -15 \checkmark \]

Trying values of x in 6x + 9 = −15

x	6x + 9	Equals -15?
-6	-27	no
-5	-21	no
-4	-15	yes
-3	-9	no
-2	-3	no

Questions

What is x in 6x + 9 = −15?

The solution of 6x + 9 = −15 is x = -4.

How do you solve 6x + 9 = −15?

Subtract 9 from both sides to get 6x = -24, then divide both sides by 6 to get x = -4.

How do I check the answer?

Replace x by -4: 6(-4) + 9 = -15, which is -15.

Solve 6x + 9 = −15

How to work it out

Trying values of x in 6x + 9 = −15

Questions

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