Solve 9x + 15 = −3

The solution of 9x + 15 = −3 is x = -2.

9x + 15 = -3\ \Rightarrow\ x = -2

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The lines y = 9x + 15 and y = -3 meet at x = -2. 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.
$9x + 15 = -3$
2
Subtract 15 from both sides:
$9x + 15 - 15 = -3 - 15 \ \Rightarrow\ 9x = -18$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{-18}{9} \ \Rightarrow\ x = -2$
4
Check: put x = -2 back into the equation.
$9\cdot(-2) + 15 = -18 + 15 = -3 \checkmark$

LaTeX source of the formulas on this page

\[ 9x + 15 = -3\ \Rightarrow\ x = -2 \]
\[ 9x + 15 = -3 \]
\[ 9x + 15 - 15 = -3 - 15 \ \Rightarrow\ 9x = -18 \]
\[ \frac{9x}{9} = \frac{-18}{9} \ \Rightarrow\ x = -2 \]
\[ 9\cdot(-2) + 15 = -18 + 15 = -3 \checkmark \]

Trying values of x in 9x + 15 = −3

x	9x + 15	Equals -3?
-4	-21	no
-3	-12	no
-2	-3	yes
-1	6	no
0	15	no

Questions

What is x in 9x + 15 = −3?

The solution of 9x + 15 = −3 is x = -2.

How do you solve 9x + 15 = −3?

Subtract 15 from both sides to get 9x = -18, then divide both sides by 9 to get x = -2.

How do I check the answer?

Replace x by -2: 9(-2) + 15 = -3, which is -3.

Solve 9x + 15 = −3

How to work it out

Trying values of x in 9x + 15 = −3

Questions

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