Solve 8x + 7 = −57

The solution of 8x + 7 = −57 is x = -8.

8x + 7 = -57\ \Rightarrow\ x = -8

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The lines y = 8x + 7 and y = -57 meet at x = -8. 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 addition, then the multiplication.
$8x + 7 = -57$
2
Subtract 7 from both sides:
$8x + 7 - 7 = -57 - 7 \ \Rightarrow\ 8x = -64$
3
Divide both sides by 8:
$\frac{8x}{8} = \frac{-64}{8} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$8\cdot(-8) + 7 = -64 + 7 = -57 \checkmark$

LaTeX source of the formulas on this page

\[ 8x + 7 = -57\ \Rightarrow\ x = -8 \]
\[ 8x + 7 = -57 \]
\[ 8x + 7 - 7 = -57 - 7 \ \Rightarrow\ 8x = -64 \]
\[ \frac{8x}{8} = \frac{-64}{8} \ \Rightarrow\ x = -8 \]
\[ 8\cdot(-8) + 7 = -64 + 7 = -57 \checkmark \]

Trying values of x in 8x + 7 = −57

x	8x + 7	Equals -57?
-10	-73	no
-9	-65	no
-8	-57	yes
-7	-49	no
-6	-41	no

Questions

What is x in 8x + 7 = −57?

The solution of 8x + 7 = −57 is x = -8.

How do you solve 8x + 7 = −57?

Subtract 7 from both sides to get 8x = -64, then divide both sides by 8 to get x = -8.

How do I check the answer?

Replace x by -8: 8(-8) + 7 = -57, which is -57.

Solve 8x + 7 = −57

How to work it out

Trying values of x in 8x + 7 = −57

Questions

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