Solve 6x + 9 = −9

The solution of 6x + 9 = −9 is x = -3.

6x + 9 = -9\ \Rightarrow\ x = -3

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The lines y = 6x + 9 and y = -9 meet at x = -3. 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.
$6x + 9 = -9$
2
Subtract 9 from both sides:
$6x + 9 - 9 = -9 - 9 \ \Rightarrow\ 6x = -18$
3
Divide both sides by 6:
$\frac{6x}{6} = \frac{-18}{6} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$6\cdot(-3) + 9 = -18 + 9 = -9 \checkmark$

LaTeX source of the formulas on this page

\[ 6x + 9 = -9\ \Rightarrow\ x = -3 \]
\[ 6x + 9 = -9 \]
\[ 6x + 9 - 9 = -9 - 9 \ \Rightarrow\ 6x = -18 \]
\[ \frac{6x}{6} = \frac{-18}{6} \ \Rightarrow\ x = -3 \]
\[ 6\cdot(-3) + 9 = -18 + 9 = -9 \checkmark \]

Trying values of x in 6x + 9 = −9

x	6x + 9	Equals -9?
-5	-21	no
-4	-15	no
-3	-9	yes
-2	-3	no
-1	3	no

Questions

What is x in 6x + 9 = −9?

The solution of 6x + 9 = −9 is x = -3.

How do you solve 6x + 9 = −9?

Subtract 9 from both sides to get 6x = -18, then divide both sides by 6 to get x = -3.

How do I check the answer?

Replace x by -3: 6(-3) + 9 = -9, which is -9.

Solve 6x + 9 = −9

How to work it out

Trying values of x in 6x + 9 = −9

Questions

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