When I do problems involving real roots, such as x = 1, why is it always x = 1 or x = - 1?

For example:

Determine the real roots of each equation:

the real root is x = 4 or x = - 4. Why is it always +/- or how can I identify this issue?

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- October 8th 2009, 01:08 PM #1

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- October 8th 2009, 01:18 PM #2

- October 8th 2009, 01:20 PM #3

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- October 8th 2009, 01:29 PM #4

- October 8th 2009, 05:31 PM #5
it is because you generated a factor of the form a^2 - b^2 = (a + b)(a - b), the difference of two squares. And why not? They are just exercises, training wheels for a rigorous future math scrimages, if you mind. And multiplicity of roots often comes out handy with some other textbooks . . . .