Solve 8x + 9 = −55

The solution of 8x + 9 = −55 is x = -8.

8x + 9 = -55\ \Rightarrow\ x = -8

Explain it step by step in chat Make a short video of it

The lines y = 8x + 9 and y = -55 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.
$8x + 9 = -55$
2
Subtract 9 from both sides:
$8x + 9 - 9 = -55 - 9 \ \Rightarrow\ 8x = -64$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-64}{8} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$8\cdot(-8) + 9 = -64 + 9 = -55 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 9 = -55\ \Rightarrow\ x = -8 \]
\[ 8x + 9 = -55 \]
\[ 8x + 9 - 9 = -55 - 9 \ \Rightarrow\ 8x = -64 \]
\[ \frac{8x}{8} = \frac{-64}{8} \ \Rightarrow\ x = -8 \]
\[ 8\cdot(-8) + 9 = -64 + 9 = -55 \checkmark \]

Trying values of x in 8x + 9 = −55

x	8x + 9	Equals -55?
-10	-71	no
-9	-63	no
-8	-55	yes
-7	-47	no
-6	-39	no

Questions

What is x in 8x + 9 = −55?

The solution of 8x + 9 = −55 is x = -8.

How do you solve 8x + 9 = −55?

Subtract 9 from both sides to get 8x = -64, then divide both sides by 8 to get x = -8.

How do I check the answer?

Replace x by -8: 8(-8) + 9 = -55, which is -55.

Solve 8x + 9 = −55

How to work it out

Trying values of x in 8x + 9 = −55

Questions

Similar equations