Solve 8x + 9 = −23

The solution of 8x + 9 = −23 is x = -4.

8x + 9 = -23\ \Rightarrow\ x = -4

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The lines y = 8x + 9 and y = -23 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 addition, then the multiplication.
$8x + 9 = -23$
2
Subtract 9 from both sides:
$8x + 9 - 9 = -23 - 9 \ \Rightarrow\ 8x = -32$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$8\cdot(-4) + 9 = -32 + 9 = -23 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 9 = -23\ \Rightarrow\ x = -4 \]
\[ 8x + 9 = -23 \]
\[ 8x + 9 - 9 = -23 - 9 \ \Rightarrow\ 8x = -32 \]
\[ \frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4 \]
\[ 8\cdot(-4) + 9 = -32 + 9 = -23 \checkmark \]

Trying values of x in 8x + 9 = −23

x	8x + 9	Equals -23?
-6	-39	no
-5	-31	no
-4	-23	yes
-3	-15	no
-2	-7	no

Questions

What is x in 8x + 9 = −23?

The solution of 8x + 9 = −23 is x = -4.

How do you solve 8x + 9 = −23?

Subtract 9 from both sides to get 8x = -32, then divide both sides by 8 to get x = -4.

How do I check the answer?

Replace x by -4: 8(-4) + 9 = -23, which is -23.

Solve 8x + 9 = −23

How to work it out

Trying values of x in 8x + 9 = −23

Questions

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