Solve 7x − 15 = −57

The solution of 7x − 15 = −57 is x = -6.

7x - 15 = -57\ \Rightarrow\ x = -6

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The lines y = 7x − 15 and y = -57 meet at x = -6. 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.
$7x - 15 = -57$
2
Add 15 to both sides:
$7x - 15 + 15 = -57 + 15 \ \Rightarrow\ 7x = -42$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{-42}{7} \ \Rightarrow\ x = -6$
4
Check: put x = -6 back into the equation.
$7\cdot(-6) - 15 = -42 - 15 = -57 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 15 = -57\ \Rightarrow\ x = -6 \]
\[ 7x - 15 = -57 \]
\[ 7x - 15 + 15 = -57 + 15 \ \Rightarrow\ 7x = -42 \]
\[ \frac{7x}{7} = \frac{-42}{7} \ \Rightarrow\ x = -6 \]
\[ 7\cdot(-6) - 15 = -42 - 15 = -57 \checkmark \]

Trying values of x in 7x − 15 = −57

x	7x − 15	Equals -57?
-8	-71	no
-7	-64	no
-6	-57	yes
-5	-50	no
-4	-43	no

Questions

What is x in 7x − 15 = −57?

The solution of 7x − 15 = −57 is x = -6.

How do you solve 7x − 15 = −57?

Add 15 to both sides to get 7x = -42, then divide both sides by 7 to get x = -6.

How do I check the answer?

Replace x by -6: 7(-6) − 15 = -57, which is -57.

Solve 7x − 15 = −57

How to work it out

Trying values of x in 7x − 15 = −57

Questions

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