Solve 8x − 15 = −55

The solution of 8x − 15 = −55 is x = -5.

8x - 15 = -55\ \Rightarrow\ x = -5

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

The lines y = 8x − 15 and y = -55 meet at x = -5. 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.
$8x - 15 = -55$
2
Add 15 to both sides:
$8x - 15 + 15 = -55 + 15 \ \Rightarrow\ 8x = -40$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-40}{8} \ \Rightarrow\ x = -5$
4
Check: put x = -5 back into the equation.
$8\cdot(-5) - 15 = -40 - 15 = -55 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 15 = -55\ \Rightarrow\ x = -5 \]
\[ 8x - 15 = -55 \]
\[ 8x - 15 + 15 = -55 + 15 \ \Rightarrow\ 8x = -40 \]
\[ \frac{8x}{8} = \frac{-40}{8} \ \Rightarrow\ x = -5 \]
\[ 8\cdot(-5) - 15 = -40 - 15 = -55 \checkmark \]

Trying values of x in 8x − 15 = −55

x	8x − 15	Equals -55?
-7	-71	no
-6	-63	no
-5	-55	yes
-4	-47	no
-3	-39	no

Questions

What is x in 8x − 15 = −55?

The solution of 8x − 15 = −55 is x = -5.

How do you solve 8x − 15 = −55?

Add 15 to both sides to get 8x = -40, then divide both sides by 8 to get x = -5.

How do I check the answer?

Replace x by -5: 8(-5) − 15 = -55, which is -55.

Solve 8x − 15 = −55

How to work it out

Trying values of x in 8x − 15 = −55

Questions

Similar equations