Solve 5x + 3 = −42

The solution of 5x + 3 = −42 is x = -9.

5x + 3 = -42\ \Rightarrow\ x = -9

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The lines y = 5x + 3 and y = -42 meet at x = -9. 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.
$5x + 3 = -42$
2
Subtract 3 from both sides:
$5x + 3 - 3 = -42 - 3 \ \Rightarrow\ 5x = -45$
3
Divide both sides by 5:
$\frac{5x}{5} = \frac{-45}{5} \ \Rightarrow\ x = -9$
4
Check: put x = -9 back into the equation.
$5\cdot(-9) + 3 = -45 + 3 = -42 \checkmark$

LaTeX source of the formulas on this page

\[ 5x + 3 = -42\ \Rightarrow\ x = -9 \]
\[ 5x + 3 = -42 \]
\[ 5x + 3 - 3 = -42 - 3 \ \Rightarrow\ 5x = -45 \]
\[ \frac{5x}{5} = \frac{-45}{5} \ \Rightarrow\ x = -9 \]
\[ 5\cdot(-9) + 3 = -45 + 3 = -42 \checkmark \]

Trying values of x in 5x + 3 = −42

x	5x + 3	Equals -42?
-11	-52	no
-10	-47	no
-9	-42	yes
-8	-37	no
-7	-32	no

Questions

What is x in 5x + 3 = −42?

The solution of 5x + 3 = −42 is x = -9.

How do you solve 5x + 3 = −42?

Subtract 3 from both sides to get 5x = -45, then divide both sides by 5 to get x = -9.

How do I check the answer?

Replace x by -9: 5(-9) + 3 = -42, which is -42.

Solve 5x + 3 = −42

How to work it out

Trying values of x in 5x + 3 = −42

Questions

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