Solve 7x − 15 = −8

The solution of 7x − 15 = −8 is x = 1.

7x - 15 = -8\ \Rightarrow\ x = 1

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The lines y = 7x − 15 and y = -8 meet at x = 1. 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.
$7x - 15 = -8$
2
Add 15 to both sides:
$7x - 15 + 15 = -8 + 15 \ \Rightarrow\ 7x = 7$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{7}{7} \ \Rightarrow\ x = 1$
4
Check: put x = 1 back into the equation.
$7\cdot1 - 15 = 7 - 15 = -8 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 15 = -8\ \Rightarrow\ x = 1 \]
\[ 7x - 15 = -8 \]
\[ 7x - 15 + 15 = -8 + 15 \ \Rightarrow\ 7x = 7 \]
\[ \frac{7x}{7} = \frac{7}{7} \ \Rightarrow\ x = 1 \]
\[ 7\cdot1 - 15 = 7 - 15 = -8 \checkmark \]

Trying values of x in 7x − 15 = −8

x	7x − 15	Equals -8?
-1	-22	no
0	-15	no
1	-8	yes
2	-1	no
3	6	no

Questions

What is x in 7x − 15 = −8?

The solution of 7x − 15 = −8 is x = 1.

How do you solve 7x − 15 = −8?

Add 15 to both sides to get 7x = 7, then divide both sides by 7 to get x = 1.

How do I check the answer?

Replace x by 1: 7(1) − 15 = -8, which is -8.

Solve 7x − 15 = −8

How to work it out

Trying values of x in 7x − 15 = −8

Questions

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