Solve 8x − 15 = −71

The solution of 8x − 15 = −71 is x = -7.

8x - 15 = -71\ \Rightarrow\ x = -7

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

The lines y = 8x − 15 and y = -71 meet at x = -7. 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.
$8x - 15 = -71$
2
Add 15 to both sides:
$8x - 15 + 15 = -71 + 15 \ \Rightarrow\ 8x = -56$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$8\cdot(-7) - 15 = -56 - 15 = -71 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 15 = -71\ \Rightarrow\ x = -7 \]
\[ 8x - 15 = -71 \]
\[ 8x - 15 + 15 = -71 + 15 \ \Rightarrow\ 8x = -56 \]
\[ \frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7 \]
\[ 8\cdot(-7) - 15 = -56 - 15 = -71 \checkmark \]

Trying values of x in 8x − 15 = −71

x	8x − 15	Equals -71?
-9	-87	no
-8	-79	no
-7	-71	yes
-6	-63	no
-5	-55	no

Questions

What is x in 8x − 15 = −71?

The solution of 8x − 15 = −71 is x = -7.

How do you solve 8x − 15 = −71?

Add 15 to both sides to get 8x = -56, then divide both sides by 8 to get x = -7.

How do I check the answer?

Replace x by -7: 8(-7) − 15 = -71, which is -71.

Solve 8x − 15 = −71

How to work it out

Trying values of x in 8x − 15 = −71

Questions

Similar equations