Solve 8x − 15 = −23

The solution of 8x − 15 = −23 is x = -1.

8x - 15 = -23\ \Rightarrow\ x = -1

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The lines y = 8x − 15 and y = -23 meet at x = -1. 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.
$8x - 15 = -23$
2
Add 15 to both sides:
$8x - 15 + 15 = -23 + 15 \ \Rightarrow\ 8x = -8$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-8}{8} \ \Rightarrow\ x = -1$
4
Check: put x = -1 back into the equation.
$8\cdot(-1) - 15 = -8 - 15 = -23 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 15 = -23\ \Rightarrow\ x = -1 \]
\[ 8x - 15 = -23 \]
\[ 8x - 15 + 15 = -23 + 15 \ \Rightarrow\ 8x = -8 \]
\[ \frac{8x}{8} = \frac{-8}{8} \ \Rightarrow\ x = -1 \]
\[ 8\cdot(-1) - 15 = -8 - 15 = -23 \checkmark \]

Trying values of x in 8x − 15 = −23

x	8x − 15	Equals -23?
-3	-39	no
-2	-31	no
-1	-23	yes
0	-15	no
1	-7	no

Questions

What is x in 8x − 15 = −23?

The solution of 8x − 15 = −23 is x = -1.

How do you solve 8x − 15 = −23?

Add 15 to both sides to get 8x = -8, then divide both sides by 8 to get x = -1.

How do I check the answer?

Replace x by -1: 8(-1) − 15 = -23, which is -23.

Solve 8x − 15 = −23

How to work it out

Trying values of x in 8x − 15 = −23

Questions

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