document.write( "Question 1209214: The radical \"sqrt%28%2880%29%2Bsqrt%281776%29%29\" can be expressed as \"sqrt%28a%29+%2Bsqrt%28b%29\", where a < b. What is the product \"ab\"? \n" ); document.write( "
Algebra.Com's Answer #847846 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "Answer: 444\r
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\n" ); document.write( "\n" ); document.write( "Explanation
\n" ); document.write( "I'll assume that a,b are positive integers.\r
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\n" ); document.write( "\n" ); document.write( "\"sqrt%2880%2Bsqrt%281776%29%29=sqrt%28a%29+%2Bsqrt%28b%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%28sqrt%2880%2Bsqrt%281776%29%29%29%5E2=%28sqrt%28a%29+%2Bsqrt%28b%29%29%5E2\" Square both sides\r
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\n" ); document.write( "\n" ); document.write( "\"80%2Bsqrt%281776%29=a%2B2%2Asqrt%28ab%29%2Bb\" \r
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\n" ); document.write( "\n" ); document.write( "\"80%2Bsqrt%281776%29=%28a%2Bb%29%2B2%2Asqrt%28ab%29\"\r
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\n" ); document.write( "\n" ); document.write( " Notice these matching pairs on either side\r
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\n" ); document.write( "\n" ); document.write( "The red and green boxes indicate that \"a%2Bb+=+80\" and \"2%2Asqrt%28ab%29+=+sqrt%281776%29\"\r
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\n" ); document.write( "\n" ); document.write( "Rewrite the 2nd equation like so
\n" ); document.write( "\"2%2Asqrt%28ab%29+=+sqrt%281776%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"%282%2Asqrt%28ab%29%29%5E2+=+%28sqrt%281776%29%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"4ab+=+1776\"\r
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\n" ); document.write( "\n" ); document.write( "\"ab+=+1776%2F4\"\r
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\n" ); document.write( "\n" ); document.write( "\"ab+=+444\"\r
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\n" ); document.write( "\n" ); document.write( "Extra info:
\n" ); document.write( "Solving the system \"system%28a%2Bb+=+80%2C+2%2Asqrt%28ab%29+=+sqrt%281776%29%29\" leads to (a,b) = (6,74) when considering a < b
\n" ); document.write( "a+b = 6+74 = 80
\n" ); document.write( "a*b = 6*74 = 444
\n" ); document.write( "\"sqrt%2880%2Bsqrt%281776%29%29=sqrt%286%29+%2Bsqrt%2874%29\"
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