Solve 12x + 9 = −87

The solution of 12x + 9 = −87 is x = -8.

12x + 9 = -87\ \Rightarrow\ x = -8

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

The lines y = 12x + 9 and y = -87 meet at x = -8. 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.
$12x + 9 = -87$
2
Subtract 9 from both sides:
$12x + 9 - 9 = -87 - 9 \ \Rightarrow\ 12x = -96$
3
Divide both sides by 12:
$\frac{12x}{12} = \frac{-96}{12} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$12\cdot(-8) + 9 = -96 + 9 = -87 \checkmark$

LaTeX source of the formulas on this page

\[ 12x + 9 = -87\ \Rightarrow\ x = -8 \]
\[ 12x + 9 = -87 \]
\[ 12x + 9 - 9 = -87 - 9 \ \Rightarrow\ 12x = -96 \]
\[ \frac{12x}{12} = \frac{-96}{12} \ \Rightarrow\ x = -8 \]
\[ 12\cdot(-8) + 9 = -96 + 9 = -87 \checkmark \]

Trying values of x in 12x + 9 = −87

x	12x + 9	Equals -87?
-10	-111	no
-9	-99	no
-8	-87	yes
-7	-75	no
-6	-63	no

Questions

What is x in 12x + 9 = −87?

The solution of 12x + 9 = −87 is x = -8.

How do you solve 12x + 9 = −87?

Subtract 9 from both sides to get 12x = -96, then divide both sides by 12 to get x = -8.

How do I check the answer?

Replace x by -8: 12(-8) + 9 = -87, which is -87.

Solve 12x + 9 = −87

How to work it out

Trying values of x in 12x + 9 = −87

Questions

Similar equations