Solve 7x − 15 = −64

The solution of 7x − 15 = −64 is x = -7.

7x - 15 = -64\ \Rightarrow\ x = -7

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The lines y = 7x − 15 and y = -64 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.
$7x - 15 = -64$
2
Add 15 to both sides:
$7x - 15 + 15 = -64 + 15 \ \Rightarrow\ 7x = -49$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-49}{7} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$7\cdot(-7) - 15 = -49 - 15 = -64 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 15 = -64\ \Rightarrow\ x = -7 \]
\[ 7x - 15 = -64 \]
\[ 7x - 15 + 15 = -64 + 15 \ \Rightarrow\ 7x = -49 \]
\[ \frac{7x}{7} = \frac{-49}{7} \ \Rightarrow\ x = -7 \]
\[ 7\cdot(-7) - 15 = -49 - 15 = -64 \checkmark \]

Trying values of x in 7x − 15 = −64

x	7x − 15	Equals -64?
-9	-78	no
-8	-71	no
-7	-64	yes
-6	-57	no
-5	-50	no

Questions

What is x in 7x − 15 = −64?

The solution of 7x − 15 = −64 is x = -7.

How do you solve 7x − 15 = −64?

Add 15 to both sides to get 7x = -49, then divide both sides by 7 to get x = -7.

How do I check the answer?

Replace x by -7: 7(-7) − 15 = -64, which is -64.

Solve 7x − 15 = −64

How to work it out

Trying values of x in 7x − 15 = −64

Questions

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