Solve 10x − 8 = −78

The solution of 10x − 8 = −78 is x = -7.

10x - 8 = -78\ \Rightarrow\ x = -7

Explain it step by step in chat Make a short video of it

The lines y = 10x − 8 and y = -78 meet at x = -7. 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.
$10x - 8 = -78$
2
Add 8 to both sides:
$10x - 8 + 8 = -78 + 8 \ \Rightarrow\ 10x = -70$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-70}{10} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$10\cdot(-7) - 8 = -70 - 8 = -78 \checkmark$

LaTeX source of the formulas on this page

\[ 10x - 8 = -78\ \Rightarrow\ x = -7 \]
\[ 10x - 8 = -78 \]
\[ 10x - 8 + 8 = -78 + 8 \ \Rightarrow\ 10x = -70 \]
\[ \frac{10x}{10} = \frac{-70}{10} \ \Rightarrow\ x = -7 \]
\[ 10\cdot(-7) - 8 = -70 - 8 = -78 \checkmark \]

Trying values of x in 10x − 8 = −78

x	10x − 8	Equals -78?
-9	-98	no
-8	-88	no
-7	-78	yes
-6	-68	no
-5	-58	no

Questions

What is x in 10x − 8 = −78?

The solution of 10x − 8 = −78 is x = -7.

How do you solve 10x − 8 = −78?

Add 8 to both sides to get 10x = -70, then divide both sides by 10 to get x = -7.

How do I check the answer?

Replace x by -7: 10(-7) − 8 = -78, which is -78.

Solve 10x − 8 = −78

How to work it out

Trying values of x in 10x − 8 = −78

Questions

Similar equations