Solve 7x + 8 = −55

The solution of 7x + 8 = −55 is x = -9.

7x + 8 = -55\ \Rightarrow\ x = -9

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The lines y = 7x + 8 and y = -55 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.
$7x + 8 = -55$
2
Subtract 8 from both sides:
$7x + 8 - 8 = -55 - 8 \ \Rightarrow\ 7x = -63$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-63}{7} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$7\cdot(-9) + 8 = -63 + 8 = -55 \checkmark$

LaTeX source of the formulas on this page

\[ 7x + 8 = -55\ \Rightarrow\ x = -9 \]
\[ 7x + 8 = -55 \]
\[ 7x + 8 - 8 = -55 - 8 \ \Rightarrow\ 7x = -63 \]
\[ \frac{7x}{7} = \frac{-63}{7} \ \Rightarrow\ x = -9 \]
\[ 7\cdot(-9) + 8 = -63 + 8 = -55 \checkmark \]

Trying values of x in 7x + 8 = −55

x	7x + 8	Equals -55?
-11	-69	no
-10	-62	no
-9	-55	yes
-8	-48	no
-7	-41	no

Questions

What is x in 7x + 8 = −55?

The solution of 7x + 8 = −55 is x = -9.

How do you solve 7x + 8 = −55?

Subtract 8 from both sides to get 7x = -63, then divide both sides by 7 to get x = -9.

How do I check the answer?

Replace x by -9: 7(-9) + 8 = -55, which is -55.

Solve 7x + 8 = −55

How to work it out

Trying values of x in 7x + 8 = −55

Questions

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