Solve 8x − 7 = −31

The solution of 8x − 7 = −31 is x = -3.

8x - 7 = -31\ \Rightarrow\ x = -3

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The lines y = 8x − 7 and y = -31 meet at x = -3. 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.
$8x - 7 = -31$
2
Add 7 to both sides:
$8x - 7 + 7 = -31 + 7 \ \Rightarrow\ 8x = -24$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-24}{8} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$8\cdot(-3) - 7 = -24 - 7 = -31 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 7 = -31\ \Rightarrow\ x = -3 \]
\[ 8x - 7 = -31 \]
\[ 8x - 7 + 7 = -31 + 7 \ \Rightarrow\ 8x = -24 \]
\[ \frac{8x}{8} = \frac{-24}{8} \ \Rightarrow\ x = -3 \]
\[ 8\cdot(-3) - 7 = -24 - 7 = -31 \checkmark \]

Trying values of x in 8x − 7 = −31

x	8x − 7	Equals -31?
-5	-47	no
-4	-39	no
-3	-31	yes
-2	-23	no
-1	-15	no

Questions

What is x in 8x − 7 = −31?

The solution of 8x − 7 = −31 is x = -3.

How do you solve 8x − 7 = −31?

Add 7 to both sides to get 8x = -24, then divide both sides by 8 to get x = -3.

How do I check the answer?

Replace x by -3: 8(-3) − 7 = -31, which is -31.

Solve 8x − 7 = −31

How to work it out

Trying values of x in 8x − 7 = −31

Questions

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