Solve 7x + 12 = −9

The solution of 7x + 12 = −9 is x = -3.

7x + 12 = -9\ \Rightarrow\ x = -3

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The lines y = 7x + 12 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.
$7x + 12 = -9$
2
Subtract 12 from both sides:
$7x + 12 - 12 = -9 - 12 \ \Rightarrow\ 7x = -21$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-21}{7} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$7\cdot(-3) + 12 = -21 + 12 = -9 \checkmark$

LaTeX source of the formulas on this page

\[ 7x + 12 = -9\ \Rightarrow\ x = -3 \]
\[ 7x + 12 = -9 \]
\[ 7x + 12 - 12 = -9 - 12 \ \Rightarrow\ 7x = -21 \]
\[ \frac{7x}{7} = \frac{-21}{7} \ \Rightarrow\ x = -3 \]
\[ 7\cdot(-3) + 12 = -21 + 12 = -9 \checkmark \]

Trying values of x in 7x + 12 = −9

x	7x + 12	Equals -9?
-5	-23	no
-4	-16	no
-3	-9	yes
-2	-2	no
-1	5	no

Questions

What is x in 7x + 12 = −9?

The solution of 7x + 12 = −9 is x = -3.

How do you solve 7x + 12 = −9?

Subtract 12 from both sides to get 7x = -21, then divide both sides by 7 to get x = -3.

How do I check the answer?

Replace x by -3: 7(-3) + 12 = -9, which is -9.

Solve 7x + 12 = −9

How to work it out

Trying values of x in 7x + 12 = −9

Questions

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