Solve 8x − 7 = −55

The solution of 8x − 7 = −55 is x = -6.

8x - 7 = -55\ \Rightarrow\ x = -6

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The lines y = 8x − 7 and y = -55 meet at x = -6. 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.
$8x - 7 = -55$
2
Add 7 to both sides:
$8x - 7 + 7 = -55 + 7 \ \Rightarrow\ 8x = -48$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-48}{8} \ \Rightarrow\ x = -6$
4
Check: put x = -6 back into the equation.
$8\cdot(-6) - 7 = -48 - 7 = -55 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 7 = -55\ \Rightarrow\ x = -6 \]
\[ 8x - 7 = -55 \]
\[ 8x - 7 + 7 = -55 + 7 \ \Rightarrow\ 8x = -48 \]
\[ \frac{8x}{8} = \frac{-48}{8} \ \Rightarrow\ x = -6 \]
\[ 8\cdot(-6) - 7 = -48 - 7 = -55 \checkmark \]

Trying values of x in 8x − 7 = −55

x	8x − 7	Equals -55?
-8	-71	no
-7	-63	no
-6	-55	yes
-5	-47	no
-4	-39	no

Questions

What is x in 8x − 7 = −55?

The solution of 8x − 7 = −55 is x = -6.

How do you solve 8x − 7 = −55?

Add 7 to both sides to get 8x = -48, then divide both sides by 8 to get x = -6.

How do I check the answer?

Replace x by -6: 8(-6) − 7 = -55, which is -55.

Solve 8x − 7 = −55

How to work it out

Trying values of x in 8x − 7 = −55

Questions

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