Solve 4x − 13 = −21

The solution of 4x − 13 = −21 is x = -2.

4x - 13 = -21\ \Rightarrow\ x = -2

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

The lines y = 4x − 13 and y = -21 meet at x = -2. 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.
$4x - 13 = -21$
2
Add 13 to both sides:
$4x - 13 + 13 = -21 + 13 \ \Rightarrow\ 4x = -8$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-8}{4} \ \Rightarrow\ x = -2$
4
Check: put x = -2 back into the equation.
$4\cdot(-2) - 13 = -8 - 13 = -21 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 13 = -21\ \Rightarrow\ x = -2 \]
\[ 4x - 13 = -21 \]
\[ 4x - 13 + 13 = -21 + 13 \ \Rightarrow\ 4x = -8 \]
\[ \frac{4x}{4} = \frac{-8}{4} \ \Rightarrow\ x = -2 \]
\[ 4\cdot(-2) - 13 = -8 - 13 = -21 \checkmark \]

Trying values of x in 4x − 13 = −21

x	4x − 13	Equals -21?
-4	-29	no
-3	-25	no
-2	-21	yes
-1	-17	no
0	-13	no

Questions

What is x in 4x − 13 = −21?

The solution of 4x − 13 = −21 is x = -2.

How do you solve 4x − 13 = −21?

Add 13 to both sides to get 4x = -8, then divide both sides by 4 to get x = -2.

How do I check the answer?

Replace x by -2: 4(-2) − 13 = -21, which is -21.

Solve 4x − 13 = −21

How to work it out

Trying values of x in 4x − 13 = −21

Questions

Similar equations