document.write( "Question 1210429: 1) Solve 2(√4x+5) - (√3x+1) = 6, where x is an integer.\r
\n" ); document.write( "\n" ); document.write( "2) Given that sinx = -3/5, where 180° ≤ x ≤ 270° and cos y = - 15/17 , where 90° ≤ y ≤ 180°. find the value of tan(x-y).
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Algebra.Com's Answer #852519 by n2(19)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "1) Solve 2(√4x+5) - (√3x+1) = 6, where x is an integer.
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\n" ); document.write( "\n" ); document.write( "Tutor @greenestamps made a great step forward, guessing or finding mentally
\n" ); document.write( "one integer solution  x = 5.\r
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\n" ); document.write( "\n" ); document.write( "But when a solution to a Math problem,  or a math equation is found by the  \" trial and error \"
\n" ); document.write( "guessing method,  always a question arises - whether this solution is unique or whether other solutions exist.\r
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\n" ); document.write( "\n" ); document.write( "There is one brilliant reasoning,  which may help in some cases,
\n" ); document.write( "and it will help to answer for this given equation.\r
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\n" ); document.write( "\n" ); document.write( "Notice that in the left side of the equation the term  \"sqrt%284x%2B1%29\"  grows  FASTER  than
\n" ); document.write( "the other term,  \"sqrt%283x%2B1%29\".     (This is obvious).\r
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\n" ); document.write( "\n" ); document.write( "AFORTIORI,  the term  \"2%2Asqrt%284x%2B1%29\"  grows even  FASTER  than the other term,  \"sqrt%283x%2B1%29\".\r
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\n" ); document.write( "\n" ); document.write( "It means that the left side of the given equation is a monotonic function of  x
\n" ); document.write( "(monotonically increases for positive values of  x).\r
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\n" ); document.write( "\n" ); document.write( "Hence,  this given equation,  having a constant value in its right side,  has a  UNIQUE  solution.\r
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\n" ); document.write( "\n" ); document.write( "In other words - if it has one solution,  then this solution is unique.\r
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\n" ); document.write( "\n" ); document.write( "Reasoning this way,  we transform our  \" trial and error \"  guessing method into  MATHEMATICALLY  STRICT   \"highlight%28highlight%28proof%29%29\".\r
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\n" ); document.write( "\n" ); document.write( "So,  x = 5  is the unique real and integer solution to this given equation.\r
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document.write( "                             Z Z Z  !\r\n" );
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document.write( "       Be careful !  That is true that in the positive 'x'-domain the left side monotonically increases.\r\n" );
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document.write( "       But what about negative 'x' ? - In this problem, the domain of negative 'x' is small and does not \r\n" );
document.write( "       make influence to the final conclusion !\r\n" );
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