Solve 4x − 15 = −47

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

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

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

LaTeX source of the formulas on this page

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

Trying values of x in 4x − 15 = −47

x	4x − 15	Equals -47?
-10	-55	no
-9	-51	no
-8	-47	yes
-7	-43	no
-6	-39	no

Questions

What is x in 4x − 15 = −47?

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

How do you solve 4x − 15 = −47?

Add 15 to both sides to get 4x = -32, then divide both sides by 4 to get x = -8.

How do I check the answer?

Replace x by -8: 4(-8) − 15 = -47, which is -47.

Solve 4x − 15 = −47

How to work it out

Trying values of x in 4x − 15 = −47

Questions

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