Solve 6x − 3 = −21
Linear equation, worked out line by line the way a teacher would write it.
Answer
| Solution | x = −3 |
Step-by-step solution
5 steps-
1 Given6 x - 3 = -21
Solve for x.
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2 Add 3 to both sides
An equation stays true as long as you do the same thing to both sides, like adding the same weight to both pans of a balance. Adding or subtracting the same amount on both sides moves a term to the other side, where it appears with the opposite sign.
6 x = -18Move the constant terms to the right.
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3 Divide both sides by 6
Dividing both sides by 6 undoes the multiplication by 6, so the variable is left on its own. Both sides change in the same way, so the equation stays true (dividing by 0 is the one thing that is never allowed).
x = \frac{-18}{6} -
4 Simplifyx = -3
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5 Check\begin{aligned}x = -3:\quad -21 = -21\quad\checkmark\end{aligned}
Substituting each solution back makes both sides equal.
Check by substitution
| x | Left side | Right side | |
|---|---|---|---|
| −3 | −21 | −21 | ✓ |
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