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Solving for x

Q:  Solve: 3 + 2(x – 5)² = 21

A:  OK, we start:

3 + 2(x – 5)² = 21

[subtract 3 from both sides]

2(x – 5)² = 18

Now, divide both sides by 2:

(x – 5)² = 9

Square-root both sides… Remember to include the +/- whenever you square-root:

√(x – 5)² = ±√9

(x – 5) = ±3

x – 5 = ±3

Add 5 to both sides:

x = ±3 + 5

So, x = 3 + 5 OR x = -3 + 5

x = 8 OR x = 2

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