Solve 7x + 15 = −13

The solution of 7x + 15 = −13 is x = -4.

7x + 15 = -13\ \Rightarrow\ x = -4

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The lines y = 7x + 15 and y = -13 meet at x = -4. 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.
$7x + 15 = -13$
2
Subtract 15 from both sides:
$7x + 15 - 15 = -13 - 15 \ \Rightarrow\ 7x = -28$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-28}{7} \ \Rightarrow\ x = -4$
4
Check: put x = -4 back into the equation.
$7\cdot(-4) + 15 = -28 + 15 = -13 \checkmark$

LaTeX source of the formulas on this page

\[ 7x + 15 = -13\ \Rightarrow\ x = -4 \]
\[ 7x + 15 = -13 \]
\[ 7x + 15 - 15 = -13 - 15 \ \Rightarrow\ 7x = -28 \]
\[ \frac{7x}{7} = \frac{-28}{7} \ \Rightarrow\ x = -4 \]
\[ 7\cdot(-4) + 15 = -28 + 15 = -13 \checkmark \]

Trying values of x in 7x + 15 = −13

x	7x + 15	Equals -13?
-6	-27	no
-5	-20	no
-4	-13	yes
-3	-6	no
-2	1	no

Questions

What is x in 7x + 15 = −13?

The solution of 7x + 15 = −13 is x = -4.

How do you solve 7x + 15 = −13?

Subtract 15 from both sides to get 7x = -28, then divide both sides by 7 to get x = -4.

How do I check the answer?

Replace x by -4: 7(-4) + 15 = -13, which is -13.

Solve 7x + 15 = −13

How to work it out

Trying values of x in 7x + 15 = −13

Questions

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