Solve 10x + 2 = −78

The solution of 10x + 2 = −78 is x = -8.

10x + 2 = -78\ \Rightarrow\ x = -8

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The lines y = 10x + 2 and y = -78 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.
$10x + 2 = -78$
2
Subtract 2 from both sides:
$10x + 2 - 2 = -78 - 2 \ \Rightarrow\ 10x = -80$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8$
4
Check: put x = -8 back into the equation.
$10\cdot(-8) + 2 = -80 + 2 = -78 \checkmark$

LaTeX source of the formulas on this page

\[ 10x + 2 = -78\ \Rightarrow\ x = -8 \]
\[ 10x + 2 = -78 \]
\[ 10x + 2 - 2 = -78 - 2 \ \Rightarrow\ 10x = -80 \]
\[ \frac{10x}{10} = \frac{-80}{10} \ \Rightarrow\ x = -8 \]
\[ 10\cdot(-8) + 2 = -80 + 2 = -78 \checkmark \]

Trying values of x in 10x + 2 = −78

x	10x + 2	Equals -78?
-10	-98	no
-9	-88	no
-8	-78	yes
-7	-68	no
-6	-58	no

Questions

What is x in 10x + 2 = −78?

The solution of 10x + 2 = −78 is x = -8.

How do you solve 10x + 2 = −78?

Subtract 2 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) + 2 = -78, which is -78.

Solve 10x + 2 = −78

How to work it out

Trying values of x in 10x + 2 = −78

Questions

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