Solve 4x − 15 = −39

The solution of 4x − 15 = −39 is x = -6.

4x - 15 = -39\ \Rightarrow\ x = -6

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

The lines y = 4x − 15 and y = -39 meet at x = -6. 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.
$4x - 15 = -39$
2
Add 15 to both sides:
$4x - 15 + 15 = -39 + 15 \ \Rightarrow\ 4x = -24$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-24}{4} \ \Rightarrow\ x = -6$
4
Check: put x = -6 back into the equation.
$4\cdot(-6) - 15 = -24 - 15 = -39 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 15 = -39\ \Rightarrow\ x = -6 \]
\[ 4x - 15 = -39 \]
\[ 4x - 15 + 15 = -39 + 15 \ \Rightarrow\ 4x = -24 \]
\[ \frac{4x}{4} = \frac{-24}{4} \ \Rightarrow\ x = -6 \]
\[ 4\cdot(-6) - 15 = -24 - 15 = -39 \checkmark \]

Trying values of x in 4x − 15 = −39

x	4x − 15	Equals -39?
-8	-47	no
-7	-43	no
-6	-39	yes
-5	-35	no
-4	-31	no

Questions

What is x in 4x − 15 = −39?

The solution of 4x − 15 = −39 is x = -6.

How do you solve 4x − 15 = −39?

Add 15 to both sides to get 4x = -24, then divide both sides by 4 to get x = -6.

How do I check the answer?

Replace x by -6: 4(-6) − 15 = -39, which is -39.

Solve 4x − 15 = −39

How to work it out

Trying values of x in 4x − 15 = −39

Questions

Similar equations