Solve 3x + 8 = −1

The solution of 3x + 8 = −1 is x = -3.

3x + 8 = -1\ \Rightarrow\ x = -3

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The lines y = 3x + 8 and y = -1 meet at x = -3. 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.
$3x + 8 = -1$
2
Subtract 8 from both sides:
$3x + 8 - 8 = -1 - 8 \ \Rightarrow\ 3x = -9$
3
Divide both sides by 3:
$\frac{3x}{3} = \frac{-9}{3} \ \Rightarrow\ x = -3$
4
Check: put x = -3 back into the equation.
$3\cdot(-3) + 8 = -9 + 8 = -1 \checkmark$

LaTeX source of the formulas on this page

\[ 3x + 8 = -1\ \Rightarrow\ x = -3 \]
\[ 3x + 8 = -1 \]
\[ 3x + 8 - 8 = -1 - 8 \ \Rightarrow\ 3x = -9 \]
\[ \frac{3x}{3} = \frac{-9}{3} \ \Rightarrow\ x = -3 \]
\[ 3\cdot(-3) + 8 = -9 + 8 = -1 \checkmark \]

Trying values of x in 3x + 8 = −1

x	3x + 8	Equals -1?
-5	-7	no
-4	-4	no
-3	-1	yes
-2	2	no
-1	5	no

Questions

What is x in 3x + 8 = −1?

The solution of 3x + 8 = −1 is x = -3.

How do you solve 3x + 8 = −1?

Subtract 8 from both sides to get 3x = -9, then divide both sides by 3 to get x = -3.

How do I check the answer?

Replace x by -3: 3(-3) + 8 = -1, which is -1.

Solve 3x + 8 = −1

How to work it out

Trying values of x in 3x + 8 = −1

Questions

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