Solve 5x + 9 = −31

The solution of 5x + 9 = −31 is x = -8.

5x + 9 = -31\ \Rightarrow\ x = -8

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The lines y = 5x + 9 and y = -31 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.
$5x + 9 = -31$
2
Subtract 9 from both sides:
$5x + 9 - 9 = -31 - 9 \ \Rightarrow\ 5x = -40$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-40}{5} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$5\cdot(-8) + 9 = -40 + 9 = -31 \checkmark$

LaTeX source of the formulas on this page

\[ 5x + 9 = -31\ \Rightarrow\ x = -8 \]
\[ 5x + 9 = -31 \]
\[ 5x + 9 - 9 = -31 - 9 \ \Rightarrow\ 5x = -40 \]
\[ \frac{5x}{5} = \frac{-40}{5} \ \Rightarrow\ x = -8 \]
\[ 5\cdot(-8) + 9 = -40 + 9 = -31 \checkmark \]

Trying values of x in 5x + 9 = −31

x	5x + 9	Equals -31?
-10	-41	no
-9	-36	no
-8	-31	yes
-7	-26	no
-6	-21	no

Questions

What is x in 5x + 9 = −31?

The solution of 5x + 9 = −31 is x = -8.

How do you solve 5x + 9 = −31?

Subtract 9 from both sides to get 5x = -40, then divide both sides by 5 to get x = -8.

How do I check the answer?

Replace x by -8: 5(-8) + 9 = -31, which is -31.

Solve 5x + 9 = −31

How to work it out

Trying values of x in 5x + 9 = −31

Questions

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