Negatives and Square Roots

Find Ask yourself? ‘What number, times itself, equals 289?

Since (17)(17) = 289, the square root of 289 is 17...

= 17

... but, there’s another number, times itself, that also equals 289.

(–17) (–17) = 289

= –17

–

You cannot find the square root of a negative number.

= undefined (not possible)

–

Find

There’s no number, times itself, that equals a negative number.

When the negative is outside the radical, your

answer is negative.

When the negative is inside the radical, your

answer is undefined.

Find

Estimating Square Roots

Ask yourself? ‘What number, times itself, equals 340 ?

Find ≈ 18

Since 340 isn’t a perfect square, what perfect squares are near 340 ?

19 =

Since is a little closer to , the square root

of 340 is approximately 18.

18 =

340

Find –

≈ –18–19 = – 18 =

nothing