Solve 7x − 15 = −71

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

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

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

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

LaTeX source of the formulas on this page

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

Trying values of x in 7x − 15 = −71

x	7x − 15	Equals -71?
-10	-85	no
-9	-78	no
-8	-71	yes
-7	-64	no
-6	-57	no

Questions

What is x in 7x − 15 = −71?

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

How do you solve 7x − 15 = −71?

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

How do I check the answer?

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

Solve 7x − 15 = −71

How to work it out

Trying values of x in 7x − 15 = −71

Questions

Similar equations