document.write( "Question 1121201: If a-b=4,ab+c^2+4=0, then find a+b.\r
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Algebra.Com's Answer #736992 by Alex.33(110)\"\" \"About 
You can put this solution on YOUR website!
First of all we can easily know a=b+4 <1>. Hence
\n" ); document.write( "\"+%28b%2B4%29%2Ab%2Bc%5E2%2B4=0+\"
\n" ); document.write( "\"+b%5E2%2Bc%5E2%2B4b%2B4=0+\"
\n" ); document.write( "\"+%28b%2B2%29%5E2%2Bc%5E2=0+\" <2>
\n" ); document.write( "Aha! Since
\n" ); document.write( "\"%28b%2B2%29%5E2%3E=0+\"
\n" ); document.write( "\"c%3E=0+\"
\n" ); document.write( "To make <2> valid both expressions must be equal to zero. Therefore
\n" ); document.write( "\"+c=0+\"
\n" ); document.write( "\"+b=-2+\"
\n" ); document.write( "And from <1> we know
\n" ); document.write( "\"+a=b%2B4=2+\"
\n" ); document.write( "\"+a%2Bb=0.+\"
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