1. Negatives and Square Roots
= 17
Find
Ask yourself?
‘What number, times itself, equals 289?
Since (17)(17) = 289,
the square root of 289 is 17... –
Find
= –17
(–17) (–17) = 289
... but, there’s another number,
times itself, that also equals 289.
When the negative is outside the radical, your answer is negative. –
Find
= undefined
(not possible)
You cannot find the square root of a negative number.
There’s no number, times itself, that equals a negative number.
When the negative is inside the radical, your answer is undefined.

2. Estimating Square Roots
≈ 18
Find
Ask yourself?
‘What number, times itself, equals 340 ?
nothing
Since 340 isn’t a perfect square, what perfect squares are near 340 ?
18 =
19 =
340
Since is a little closer to , the square root
of 340 is approximately 18.
Find –
≈ –18
–19 =
– 18 =