Solve 4x + 8 = −28

The solution of 4x + 8 = −28 is x = -9.

4x + 8 = -28\ \Rightarrow\ x = -9

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The lines y = 4x + 8 and y = -28 meet at x = -9. 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 addition, then the multiplication.
$4x + 8 = -28$
2
Subtract 8 from both sides:
$4x + 8 - 8 = -28 - 8 \ \Rightarrow\ 4x = -36$
3
Divide both sides by 4:
$\frac{4x}{4} = \frac{-36}{4} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$4\cdot(-9) + 8 = -36 + 8 = -28 \checkmark$

LaTeX source of the formulas on this page

\[ 4x + 8 = -28\ \Rightarrow\ x = -9 \]
\[ 4x + 8 = -28 \]
\[ 4x + 8 - 8 = -28 - 8 \ \Rightarrow\ 4x = -36 \]
\[ \frac{4x}{4} = \frac{-36}{4} \ \Rightarrow\ x = -9 \]
\[ 4\cdot(-9) + 8 = -36 + 8 = -28 \checkmark \]

Trying values of x in 4x + 8 = −28

x	4x + 8	Equals -28?
-11	-36	no
-10	-32	no
-9	-28	yes
-8	-24	no
-7	-20	no

Questions

What is x in 4x + 8 = −28?

The solution of 4x + 8 = −28 is x = -9.

How do you solve 4x + 8 = −28?

Subtract 8 from both sides to get 4x = -36, then divide both sides by 4 to get x = -9.

How do I check the answer?

Replace x by -9: 4(-9) + 8 = -28, which is -28.

Solve 4x + 8 = −28

How to work it out

Trying values of x in 4x + 8 = −28

Questions

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