document.write( "Question 1208295: If 2¹³ + 2¹⁰ + 2ˣ = y²,
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document.write( "find x and y. \n" );
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Algebra.Com's Answer #846623 by math_tutor2020(3816)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "I'll assume x and y are nonnegative integers. \n" ); document.write( "There might be a more clever and elegant solution, but I'm going to check possible values of x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If x = 0, then, \n" ); document.write( "2^13 + 2^10 + 2^x \n" ); document.write( "= 2^13 + 2^10 + 2^0 \n" ); document.write( "= 9217 \n" ); document.write( "And, \n" ); document.write( "sqrt(9217) = 96.0052 approximately \n" ); document.write( "Since the square root result isn't a whole number, this shows 9217 isn't a perfect square. \n" ); document.write( "y^2 = 9217 doesn't have an integer solution. \n" ); document.write( "x = 0 won't pair with an integer y value. \n" ); document.write( "We can rule out x = 0.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's try x = 1. \n" ); document.write( "2^13 + 2^10 + 2^x \n" ); document.write( "= 2^13 + 2^10 + 2^1 \n" ); document.write( "= 9218 \n" ); document.write( "And, \n" ); document.write( "sqrt(9218) = 96.0104 approximately \n" ); document.write( "Same idea as the previous paragraph. \n" ); document.write( "We can rule out x = 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's try x = 2. \n" ); document.write( "2^13 + 2^10 + 2^x \n" ); document.write( "= 2^13 + 2^10 + 2^2 \n" ); document.write( "= 9220 \n" ); document.write( "And, \n" ); document.write( "sqrt(9220) = 96.0208 approximately \n" ); document.write( "We can rule out x = 2 for similar reasoning as the previous paragraphs.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "And so on. \n" ); document.write( "Keep this process going until reaching x = 14. \n" ); document.write( "Use of a spreadsheet is strongly recommended to make this process very quick. \n" ); document.write( "Alternatively you can use a programming language such as Python to write up a quick script. \n" ); document.write( "2^13 + 2^10 + 2^x \n" ); document.write( "= 2^13 + 2^10 + 2^14 \n" ); document.write( "= 25600 \n" ); document.write( "And, \n" ); document.write( "sqrt(25600) = 160 exactly \n" ); document.write( "We finally get an integer result. \n" ); document.write( "This proves that x = 14 and y = 160 is one ordered pair solution. \n" ); document.write( "2^13 + 2^10 + 2^14 = 160^2 \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There might be other solutions. \n" ); document.write( " \n" ); document.write( " |