Solve 10x + 8 = −72

The solution of 10x + 8 = −72 is x = -8.

10x + 8 = -72\ \Rightarrow\ x = -8

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The lines y = 10x + 8 and y = -72 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.
$10x + 8 = -72$
2
Subtract 8 from both sides:
$10x + 8 - 8 = -72 - 8 \ \Rightarrow\ 10x = -80$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$10\cdot(-8) + 8 = -80 + 8 = -72 \checkmark$

LaTeX source of the formulas on this page

\[ 10x + 8 = -72\ \Rightarrow\ x = -8 \]
\[ 10x + 8 = -72 \]
\[ 10x + 8 - 8 = -72 - 8 \ \Rightarrow\ 10x = -80 \]
\[ \frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8 \]
\[ 10\cdot(-8) + 8 = -80 + 8 = -72 \checkmark \]

Trying values of x in 10x + 8 = −72

x	10x + 8	Equals -72?
-10	-92	no
-9	-82	no
-8	-72	yes
-7	-62	no
-6	-52	no

Questions

What is x in 10x + 8 = −72?

The solution of 10x + 8 = −72 is x = -8.

How do you solve 10x + 8 = −72?

Subtract 8 from both sides to get 10x = -80, then divide both sides by 10 to get x = -8.

How do I check the answer?

Replace x by -8: 10(-8) + 8 = -72, which is -72.

Solve 10x + 8 = −72

How to work it out

Trying values of x in 10x + 8 = −72

Questions

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