Solve 5x − 7 = −42

The solution of 5x − 7 = −42 is x = -7.

5x - 7 = -42\ \Rightarrow\ x = -7

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The lines y = 5x − 7 and y = -42 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.
$5x - 7 = -42$
2
Add 7 to both sides:
$5x - 7 + 7 = -42 + 7 \ \Rightarrow\ 5x = -35$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-35}{5} \ \Rightarrow\ x = -7$
4
Check: put x = -7 back into the equation.
$5\cdot(-7) - 7 = -35 - 7 = -42 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 7 = -42\ \Rightarrow\ x = -7 \]
\[ 5x - 7 = -42 \]
\[ 5x - 7 + 7 = -42 + 7 \ \Rightarrow\ 5x = -35 \]
\[ \frac{5x}{5} = \frac{-35}{5} \ \Rightarrow\ x = -7 \]
\[ 5\cdot(-7) - 7 = -35 - 7 = -42 \checkmark \]

Trying values of x in 5x − 7 = −42

x	5x − 7	Equals -42?
-9	-52	no
-8	-47	no
-7	-42	yes
-6	-37	no
-5	-32	no

Questions

What is x in 5x − 7 = −42?

The solution of 5x − 7 = −42 is x = -7.

How do you solve 5x − 7 = −42?

Add 7 to both sides to get 5x = -35, then divide both sides by 5 to get x = -7.

How do I check the answer?

Replace x by -7: 5(-7) − 7 = -42, which is -42.

Solve 5x − 7 = −42

How to work it out

Trying values of x in 5x − 7 = −42

Questions

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