An easy Math task with deduction anyone?

Mathematics
Tutor: None Selected Time limit: 1 Day

http://i59.tinypic.com/vdp8pf.jpg Thanks in advance!

Oct 5th, 2015

Hello!

(√7 + √2)*(9 - 2√14)/(√7 - √2) = ?

The interesting part is 9-2√14. 14 is 7*2 and 9 is 7+2, so we have

a^2 + b^2 - 2*ab for a = √7 and b = √2, i.e.

(a-b)^2 = (√7 - √2)^2.

Then one (√7 - √2) goes off numerator and denominator and remains only

(√7 + √2)*(√7 - √2) which is (√7)^2 - (√2)^2 = 7 - 2 = 5.

Please ask if something is unclear.
Oct 5th, 2015

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Oct 5th, 2015
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