Solve 9x − 15 = −51

The solution of 9x − 15 = −51 is x = -4.

9x - 15 = -51\ \Rightarrow\ x = -4

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The lines y = 9x − 15 and y = -51 meet at x = -4. 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 subtraction, then the multiplication.
$9x - 15 = -51$
2
Add 15 to both sides:
$9x - 15 + 15 = -51 + 15 \ \Rightarrow\ 9x = -36$
3
Divide both sides by 9:
$\frac{9x}{9} = \frac{-36}{9} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$9\cdot(-4) - 15 = -36 - 15 = -51 \checkmark$

LaTeX source of the formulas on this page

\[ 9x - 15 = -51\ \Rightarrow\ x = -4 \]
\[ 9x - 15 = -51 \]
\[ 9x - 15 + 15 = -51 + 15 \ \Rightarrow\ 9x = -36 \]
\[ \frac{9x}{9} = \frac{-36}{9} \ \Rightarrow\ x = -4 \]
\[ 9\cdot(-4) - 15 = -36 - 15 = -51 \checkmark \]

Trying values of x in 9x − 15 = −51

x	9x − 15	Equals -51?
-6	-69	no
-5	-60	no
-4	-51	yes
-3	-42	no
-2	-33	no

Questions

What is x in 9x − 15 = −51?

The solution of 9x − 15 = −51 is x = -4.

How do you solve 9x − 15 = −51?

Add 15 to both sides to get 9x = -36, then divide both sides by 9 to get x = -4.

How do I check the answer?

Replace x by -4: 9(-4) − 15 = -51, which is -51.

Solve 9x − 15 = −51

How to work it out

Trying values of x in 9x − 15 = −51

Questions

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