Solve 2x + 1 = −7

The solution of 2x + 1 = −7 is x = -4.

2x + 1 = -7\ \Rightarrow\ x = -4

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The lines y = 2x + 1 and y = -7 meet at x = -4. 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.
$2x + 1 = -7$
2
Subtract 1 from both sides:
$2x + 1 - 1 = -7 - 1 \ \Rightarrow\ 2x = -8$
3
Divide both sides by 2:
$\frac{2x}{2} = \frac{-8}{2} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$2\cdot(-4) + 1 = -8 + 1 = -7 \checkmark$

LaTeX source of the formulas on this page

\[ 2x + 1 = -7\ \Rightarrow\ x = -4 \]
\[ 2x + 1 = -7 \]
\[ 2x + 1 - 1 = -7 - 1 \ \Rightarrow\ 2x = -8 \]
\[ \frac{2x}{2} = \frac{-8}{2} \ \Rightarrow\ x = -4 \]
\[ 2\cdot(-4) + 1 = -8 + 1 = -7 \checkmark \]

Trying values of x in 2x + 1 = −7

x	2x + 1	Equals -7?
-6	-11	no
-5	-9	no
-4	-7	yes
-3	-5	no
-2	-3	no

Questions

What is x in 2x + 1 = −7?

The solution of 2x + 1 = −7 is x = -4.

How do you solve 2x + 1 = −7?

Subtract 1 from both sides to get 2x = -8, then divide both sides by 2 to get x = -4.

How do I check the answer?

Replace x by -4: 2(-4) + 1 = -7, which is -7.

Solve 2x + 1 = −7

How to work it out

Trying values of x in 2x + 1 = −7

Questions

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