Solve 4x − 13 = −45

The solution of 4x − 13 = −45 is x = -8.

4x - 13 = -45\ \Rightarrow\ x = -8

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The lines y = 4x − 13 and y = -45 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.
$4x - 13 = -45$
2
Add 13 to both sides:
$4x - 13 + 13 = -45 + 13 \ \Rightarrow\ 4x = -32$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-32}{4} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$4\cdot(-8) - 13 = -32 - 13 = -45 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 13 = -45\ \Rightarrow\ x = -8 \]
\[ 4x - 13 = -45 \]
\[ 4x - 13 + 13 = -45 + 13 \ \Rightarrow\ 4x = -32 \]
\[ \frac{4x}{4} = \frac{-32}{4} \ \Rightarrow\ x = -8 \]
\[ 4\cdot(-8) - 13 = -32 - 13 = -45 \checkmark \]

Trying values of x in 4x − 13 = −45

x	4x − 13	Equals -45?
-10	-53	no
-9	-49	no
-8	-45	yes
-7	-41	no
-6	-37	no

Questions

What is x in 4x − 13 = −45?

The solution of 4x − 13 = −45 is x = -8.

How do you solve 4x − 13 = −45?

Add 13 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) − 13 = -45, which is -45.

Solve 4x − 13 = −45

How to work it out

Trying values of x in 4x − 13 = −45

Questions

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