Can any kind soul help me in the below?

Please assist in (b)

a) Factorise t^4 - 16

b) If (x + 2/x)^2 = 36, then what is (x^2 + 2/x^2)^2?

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- Feb 11th 2010, 12:51 AM #1

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- Feb 11th 2010, 01:09 AM #2
Well, a) is easy, if you note that (or ).

__Second question__: I guess there is another more clever way to do this but I would have solved for first, then evaluated.

Since , we have , thus , therefore , so , and so, .

By means of the quadratic formula (for example), you find that equals that value and that value, then you substitute your results back into the second equation and evaluate.

Does that make sense ?

- Feb 11th 2010, 01:52 AM #3

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- Feb 11th 2010, 03:43 AM #4

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- Feb 11th 2010, 06:24 AM #5

- Feb 11th 2010, 01:31 PM #6

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