Solve 8x − 9 = −49

The solution of 8x − 9 = −49 is x = -5.

8x - 9 = -49\ \Rightarrow\ x = -5

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The lines y = 8x − 9 and y = -49 meet at x = -5. 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.
$8x - 9 = -49$
2
Add 9 to both sides:
$8x - 9 + 9 = -49 + 9 \ \Rightarrow\ 8x = -40$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-40}{8} \ \Rightarrow\ x = -5$
4
Check: put x = -5 back into the equation.
$8\cdot(-5) - 9 = -40 - 9 = -49 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 9 = -49\ \Rightarrow\ x = -5 \]
\[ 8x - 9 = -49 \]
\[ 8x - 9 + 9 = -49 + 9 \ \Rightarrow\ 8x = -40 \]
\[ \frac{8x}{8} = \frac{-40}{8} \ \Rightarrow\ x = -5 \]
\[ 8\cdot(-5) - 9 = -40 - 9 = -49 \checkmark \]

Trying values of x in 8x − 9 = −49

x	8x − 9	Equals -49?
-7	-65	no
-6	-57	no
-5	-49	yes
-4	-41	no
-3	-33	no

Questions

What is x in 8x − 9 = −49?

The solution of 8x − 9 = −49 is x = -5.

How do you solve 8x − 9 = −49?

Add 9 to both sides to get 8x = -40, then divide both sides by 8 to get x = -5.

How do I check the answer?

Replace x by -5: 8(-5) − 9 = -49, which is -49.

Solve 8x − 9 = −49

How to work it out

Trying values of x in 8x − 9 = −49

Questions

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