Solve 7x − 8 = −71

The solution of 7x − 8 = −71 is x = -9.

7x - 8 = -71\ \Rightarrow\ x = -9

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The lines y = 7x − 8 and y = -71 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 subtraction, then the multiplication.
$7x - 8 = -71$
2
Add 8 to both sides:
$7x - 8 + 8 = -71 + 8 \ \Rightarrow\ 7x = -63$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-63}{7} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$7\cdot(-9) - 8 = -63 - 8 = -71 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 8 = -71\ \Rightarrow\ x = -9 \]
\[ 7x - 8 = -71 \]
\[ 7x - 8 + 8 = -71 + 8 \ \Rightarrow\ 7x = -63 \]
\[ \frac{7x}{7} = \frac{-63}{7} \ \Rightarrow\ x = -9 \]
\[ 7\cdot(-9) - 8 = -63 - 8 = -71 \checkmark \]

Trying values of x in 7x − 8 = −71

x	7x − 8	Equals -71?
-11	-85	no
-10	-78	no
-9	-71	yes
-8	-64	no
-7	-57	no

Questions

What is x in 7x − 8 = −71?

The solution of 7x − 8 = −71 is x = -9.

How do you solve 7x − 8 = −71?

Add 8 to 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 = -71, which is -71.

Solve 7x − 8 = −71

How to work it out

Trying values of x in 7x − 8 = −71

Questions

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