Solve 9x + 12 = −15

The solution of 9x + 12 = −15 is x = -3.

9x + 12 = -15\ \Rightarrow\ x = -3

Explain it step by step in chat Make a short video of it

The lines y = 9x + 12 and y = -15 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.
$9x + 12 = -15$
2
Subtract 12 from both sides:
$9x + 12 - 12 = -15 - 12 \ \Rightarrow\ 9x = -27$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{-27}{9} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$9\cdot(-3) + 12 = -27 + 12 = -15 \checkmark$

LaTeX source of the formulas on this page

\[ 9x + 12 = -15\ \Rightarrow\ x = -3 \]
\[ 9x + 12 = -15 \]
\[ 9x + 12 - 12 = -15 - 12 \ \Rightarrow\ 9x = -27 \]
\[ \frac{9x}{9} = \frac{-27}{9} \ \Rightarrow\ x = -3 \]
\[ 9\cdot(-3) + 12 = -27 + 12 = -15 \checkmark \]

Trying values of x in 9x + 12 = −15

x	9x + 12	Equals -15?
-5	-33	no
-4	-24	no
-3	-15	yes
-2	-6	no
-1	3	no

Questions

What is x in 9x + 12 = −15?

The solution of 9x + 12 = −15 is x = -3.

How do you solve 9x + 12 = −15?

Subtract 12 from both sides to get 9x = -27, then divide both sides by 9 to get x = -3.

How do I check the answer?

Replace x by -3: 9(-3) + 12 = -15, which is -15.

Solve 9x + 12 = −15

How to work it out

Trying values of x in 9x + 12 = −15

Questions

Similar equations