Solve 10x + 13 = −77

The solution of 10x + 13 = −77 is x = -9.

10x + 13 = -77\ \Rightarrow\ x = -9

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The lines y = 10x + 13 and y = -77 meet at x = -9. 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.
$10x + 13 = -77$
2
Subtract 13 from both sides:
$10x + 13 - 13 = -77 - 13 \ \Rightarrow\ 10x = -90$
3
Divide both sides by 10:
$\frac{10x}{10} = \frac{-90}{10} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$10\cdot(-9) + 13 = -90 + 13 = -77 \checkmark$

LaTeX source of the formulas on this page

\[ 10x + 13 = -77\ \Rightarrow\ x = -9 \]
\[ 10x + 13 = -77 \]
\[ 10x + 13 - 13 = -77 - 13 \ \Rightarrow\ 10x = -90 \]
\[ \frac{10x}{10} = \frac{-90}{10} \ \Rightarrow\ x = -9 \]
\[ 10\cdot(-9) + 13 = -90 + 13 = -77 \checkmark \]

Trying values of x in 10x + 13 = −77

x	10x + 13	Equals -77?
-11	-97	no
-10	-87	no
-9	-77	yes
-8	-67	no
-7	-57	no

Questions

What is x in 10x + 13 = −77?

The solution of 10x + 13 = −77 is x = -9.

How do you solve 10x + 13 = −77?

Subtract 13 from both sides to get 10x = -90, then divide both sides by 10 to get x = -9.

How do I check the answer?

Replace x by -9: 10(-9) + 13 = -77, which is -77.

Solve 10x + 13 = −77

How to work it out

Trying values of x in 10x + 13 = −77

Questions

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