Solve 8x − 15 = −47

The solution of 8x − 15 = −47 is x = -4.

8x - 15 = -47\ \Rightarrow\ x = -4

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The lines y = 8x − 15 and y = -47 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.
$8x - 15 = -47$
2
Add 15 to both sides:
$8x - 15 + 15 = -47 + 15 \ \Rightarrow\ 8x = -32$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$8\cdot(-4) - 15 = -32 - 15 = -47 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 15 = -47\ \Rightarrow\ x = -4 \]
\[ 8x - 15 = -47 \]
\[ 8x - 15 + 15 = -47 + 15 \ \Rightarrow\ 8x = -32 \]
\[ \frac{8x}{8} = \frac{-32}{8} \ \Rightarrow\ x = -4 \]
\[ 8\cdot(-4) - 15 = -32 - 15 = -47 \checkmark \]

Trying values of x in 8x − 15 = −47

x	8x − 15	Equals -47?
-6	-63	no
-5	-55	no
-4	-47	yes
-3	-39	no
-2	-31	no

Questions

What is x in 8x − 15 = −47?

The solution of 8x − 15 = −47 is x = -4.

How do you solve 8x − 15 = −47?

Add 15 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) − 15 = -47, which is -47.

Solve 8x − 15 = −47

How to work it out

Trying values of x in 8x − 15 = −47

Questions

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