Solve 8x − 7 = −39

The solution of 8x − 7 = −39 is x = -4.

8x - 7 = -39\ \Rightarrow\ x = -4

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

The lines y = 8x − 7 and y = -39 meet at x = -4. 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.
$8x - 7 = -39$
2
Add 7 to both sides:
$8x - 7 + 7 = -39 + 7 \ \Rightarrow\ 8x = -32$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$8\cdot(-4) - 7 = -32 - 7 = -39 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 7 = -39\ \Rightarrow\ x = -4 \]
\[ 8x - 7 = -39 \]
\[ 8x - 7 + 7 = -39 + 7 \ \Rightarrow\ 8x = -32 \]
\[ \frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4 \]
\[ 8\cdot(-4) - 7 = -32 - 7 = -39 \checkmark \]

Trying values of x in 8x − 7 = −39

x	8x − 7	Equals -39?
-6	-55	no
-5	-47	no
-4	-39	yes
-3	-31	no
-2	-23	no

Questions

What is x in 8x − 7 = −39?

The solution of 8x − 7 = −39 is x = -4.

How do you solve 8x − 7 = −39?

Add 7 to both sides to get 8x = -32, then divide both sides by 8 to get x = -4.

How do I check the answer?

Replace x by -4: 8(-4) − 7 = -39, which is -39.

Solve 8x − 7 = −39

How to work it out

Trying values of x in 8x − 7 = −39

Questions

Similar equations