Solve 5x − 12 = −42

The solution of 5x − 12 = −42 is x = -6.

5x - 12 = -42\ \Rightarrow\ x = -6

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The lines y = 5x − 12 and y = -42 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.
$5x - 12 = -42$
2
Add 12 to both sides:
$5x - 12 + 12 = -42 + 12 \ \Rightarrow\ 5x = -30$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-30}{5} \ \Rightarrow\ x = -6$
4
Check: put x = -6 back into the equation.
$5\cdot(-6) - 12 = -30 - 12 = -42 \checkmark$

LaTeX source of the formulas on this page

\[ 5x - 12 = -42\ \Rightarrow\ x = -6 \]
\[ 5x - 12 = -42 \]
\[ 5x - 12 + 12 = -42 + 12 \ \Rightarrow\ 5x = -30 \]
\[ \frac{5x}{5} = \frac{-30}{5} \ \Rightarrow\ x = -6 \]
\[ 5\cdot(-6) - 12 = -30 - 12 = -42 \checkmark \]

Trying values of x in 5x − 12 = −42

x	5x − 12	Equals -42?
-8	-52	no
-7	-47	no
-6	-42	yes
-5	-37	no
-4	-32	no

Questions

What is x in 5x − 12 = −42?

The solution of 5x − 12 = −42 is x = -6.

How do you solve 5x − 12 = −42?

Add 12 to both sides to get 5x = -30, then divide both sides by 5 to get x = -6.

How do I check the answer?

Replace x by -6: 5(-6) − 12 = -42, which is -42.

Solve 5x − 12 = −42

How to work it out

Trying values of x in 5x − 12 = −42

Questions

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