Solve 4x − 15 = −43

The solution of 4x − 15 = −43 is x = -7.

4x - 15 = -43\ \Rightarrow\ x = -7

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The lines y = 4x − 15 and y = -43 meet at x = -7. 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.
$4x - 15 = -43$
2
Add 15 to both sides:
$4x - 15 + 15 = -43 + 15 \ \Rightarrow\ 4x = -28$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-28}{4} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$4\cdot(-7) - 15 = -28 - 15 = -43 \checkmark$

LaTeX source of the formulas on this page

\[ 4x - 15 = -43\ \Rightarrow\ x = -7 \]
\[ 4x - 15 = -43 \]
\[ 4x - 15 + 15 = -43 + 15 \ \Rightarrow\ 4x = -28 \]
\[ \frac{4x}{4} = \frac{-28}{4} \ \Rightarrow\ x = -7 \]
\[ 4\cdot(-7) - 15 = -28 - 15 = -43 \checkmark \]

Trying values of x in 4x − 15 = −43

x	4x − 15	Equals -43?
-9	-51	no
-8	-47	no
-7	-43	yes
-6	-39	no
-5	-35	no

Questions

What is x in 4x − 15 = −43?

The solution of 4x − 15 = −43 is x = -7.

How do you solve 4x − 15 = −43?

Add 15 to both sides to get 4x = -28, then divide both sides by 4 to get x = -7.

How do I check the answer?

Replace x by -7: 4(-7) − 15 = -43, which is -43.

Solve 4x − 15 = −43

How to work it out

Trying values of x in 4x − 15 = −43

Questions

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