Solve 8x − 9 = −65

The solution of 8x − 9 = −65 is x = -7.

8x - 9 = -65\ \Rightarrow\ x = -7

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The lines y = 8x − 9 and y = -65 meet at x = -7. 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.
$8x - 9 = -65$
2
Add 9 to both sides:
$8x - 9 + 9 = -65 + 9 \ \Rightarrow\ 8x = -56$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$8\cdot(-7) - 9 = -56 - 9 = -65 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 9 = -65\ \Rightarrow\ x = -7 \]
\[ 8x - 9 = -65 \]
\[ 8x - 9 + 9 = -65 + 9 \ \Rightarrow\ 8x = -56 \]
\[ \frac{8x}{8} = \frac{-56}{8} \ \Rightarrow\ x = -7 \]
\[ 8\cdot(-7) - 9 = -56 - 9 = -65 \checkmark \]

Trying values of x in 8x − 9 = −65

x	8x − 9	Equals -65?
-9	-81	no
-8	-73	no
-7	-65	yes
-6	-57	no
-5	-49	no

Questions

What is x in 8x − 9 = −65?

The solution of 8x − 9 = −65 is x = -7.

How do you solve 8x − 9 = −65?

Add 9 to both sides to get 8x = -56, then divide both sides by 8 to get x = -7.

How do I check the answer?

Replace x by -7: 8(-7) − 9 = -65, which is -65.

Solve 8x − 9 = −65

How to work it out

Trying values of x in 8x − 9 = −65

Questions

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