Solve 8x − 9 = −57

The solution of 8x − 9 = −57 is x = -6.

8x - 9 = -57\ \Rightarrow\ x = -6

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The lines y = 8x − 9 and y = -57 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.
$8x - 9 = -57$
2
Add 9 to both sides:
$8x - 9 + 9 = -57 + 9 \ \Rightarrow\ 8x = -48$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-48}{8} \ \Rightarrow\ x = -6$
4
Check: put x = -6 back into the equation.
$8\cdot(-6) - 9 = -48 - 9 = -57 \checkmark$

LaTeX source of the formulas on this page

\[ 8x - 9 = -57\ \Rightarrow\ x = -6 \]
\[ 8x - 9 = -57 \]
\[ 8x - 9 + 9 = -57 + 9 \ \Rightarrow\ 8x = -48 \]
\[ \frac{8x}{8} = \frac{-48}{8} \ \Rightarrow\ x = -6 \]
\[ 8\cdot(-6) - 9 = -48 - 9 = -57 \checkmark \]

Trying values of x in 8x − 9 = −57

x	8x − 9	Equals -57?
-8	-73	no
-7	-65	no
-6	-57	yes
-5	-49	no
-4	-41	no

Questions

What is x in 8x − 9 = −57?

The solution of 8x − 9 = −57 is x = -6.

How do you solve 8x − 9 = −57?

Add 9 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) − 9 = -57, which is -57.

Solve 8x − 9 = −57

How to work it out

Trying values of x in 8x − 9 = −57

Questions

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