gwe9766 Posted May 27, 2010 Share Posted May 27, 2010 Example comparison question: Column A: (2^30 - 2^29)/2 Column B: 2^28 The answer is C. Can someone please explain why these 2 columns are the same? Also any insight on adding or subtracting exponents with the same base would be useful. Thanks! Quote Link to comment Share on other sites More sharing options...
sharmilastephen Posted May 27, 2010 Share Posted May 27, 2010 Hi Column A : (2^30-2^29)/2 = 2^29-2^28 = 2^28(2-1) = 2^28 (1) = 2^28 Column B: 2^28 So the answer is C both are equal Quote Link to comment Share on other sites More sharing options...
kobra Posted May 28, 2010 Share Posted May 28, 2010 learn this handy formula x^a - x^b = (x^(a-b)-1)(x^b) x^a +x^b = (x^(a-b)+1)(x^b) a>b Quote Link to comment Share on other sites More sharing options...
rina777 Posted May 29, 2010 Share Posted May 29, 2010 (2^30-2^29)/2 = 2^28(4-2)/2 = 2^28 so A=B and the answer is C Quote Link to comment Share on other sites More sharing options...
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