Answers

2014-08-03T13:20:01+08:00
A^2 - 9 x^2 - 16 X^2 - 36 a^2 - b^2 x^2 - y^2
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2014-08-03T13:21:54+08:00
(a+3)(a-3)= a²-9
(x+4)(x-4)= x²-16
(x+6)(x-6)= x²-36
(a+b)(a-b)= a²-b²
(x+y)(x-y)= x²-y²

Just square the first and last terms and use the negative sign. :)
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