Solve 8x − 13 = −85

The solution of 8x − 13 = −85 is x = -9.

8x - 13 = -85\ \Rightarrow\ x = -9

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

The lines y = 8x − 13 and y = -85 meet at x = -9. 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.
$8x - 13 = -85$
2
Add 13 to both sides:
$8x - 13 + 13 = -85 + 13 \ \Rightarrow\ 8x = -72$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-72}{8} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$8\cdot(-9) - 13 = -72 - 13 = -85 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 13 = -85\ \Rightarrow\ x = -9 \]
\[ 8x - 13 = -85 \]
\[ 8x - 13 + 13 = -85 + 13 \ \Rightarrow\ 8x = -72 \]
\[ \frac{8x}{8} = \frac{-72}{8} \ \Rightarrow\ x = -9 \]
\[ 8\cdot(-9) - 13 = -72 - 13 = -85 \checkmark \]

Trying values of x in 8x − 13 = −85

x	8x − 13	Equals -85?
-11	-101	no
-10	-93	no
-9	-85	yes
-8	-77	no
-7	-69	no

Questions

What is x in 8x − 13 = −85?

The solution of 8x − 13 = −85 is x = -9.

How do you solve 8x − 13 = −85?

Add 13 to both sides to get 8x = -72, then divide both sides by 8 to get x = -9.

How do I check the answer?

Replace x by -9: 8(-9) − 13 = -85, which is -85.

Solve 8x − 13 = −85

How to work it out

Trying values of x in 8x − 13 = −85

Questions

Similar equations