document.write( "Question 686643: one of the questions to my homewok that i am having trouble with answering was r^2-3r/5+2/25=0 and the homework asks to find the value of the discriminant and describe the nature of the roots of each quadratic equation Then solve the equation and ive tried various ways but i have no confidence so o=if you can help that would be great \n" ); document.write( "
Algebra.Com's Answer #424863 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
When you have the equation in the form
\n" ); document.write( "\"+y+=+a%2Ax%5E2+%2B+b%2Ax+%2B+c+\", the the discriminant is
\n" ); document.write( "\"+b%5E2+-+4%2Aa%2Ac+\"
\n" ); document.write( "The rules are:
\n" ); document.write( "(1) If \"+b%5E2+-+4%2Aa%2Ac+%3C+0+\", then there are 2 imaginary roots
\n" ); document.write( "(2) If \"+b%5E2+-+4%2Aa%2Ac+%3E+0+\", then there are 2 real roots
\n" ); document.write( "(3) If \"+b%5E2+-+4%2Aa%2Ac+=+0+\", then there is a single real root ( called a double root )
\n" ); document.write( "-----------------------
\n" ); document.write( "Your equation is:
\n" ); document.write( "\"+f%28r%29+=+r%5E2+-+%283%2F5%29%2Ar+%2B+2%2F25+\"
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+2%2F25+=+0+\"
\n" ); document.write( "( note that this is saying \"+f%28r%29+=+0+\", which means that the
\n" ); document.write( "values of \"r\" that you find will be the x-crossings which are the roots )
\n" ); document.write( "------------------------
\n" ); document.write( "The fact that you have \"r\" and not \"x\" doesn't matter
\n" ); document.write( "The form is still \"+a%2Ax%5E2+%2B+b%2Ax+%2B+c+=+0+\"
\n" ); document.write( "\"+a+=+1+\"
\n" ); document.write( "\"+b+=+3%2F5+\"
\n" ); document.write( "\"+c+=+2%2F25+\"
\n" ); document.write( "Now just plug these into the discriminant
\n" ); document.write( "\"+b%5E2+-+4%2Aa%2Ac+=+%283%2F5%29%5E2+-+4%2A1%2A%282%2F25%29+\"
\n" ); document.write( "\"+b%5E2+-+4%2Aa%2Ac+=+9%2F25+-+8%2F25+\"
\n" ); document.write( "\"+b%5E2+-+4%2Aa%2Ac+=+1%2F25+\"
\n" ); document.write( "This is a positive result, so there are 2 roots, and they are real
\n" ); document.write( "Now to solve equation:
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+2%2F25+=+0+\"
\n" ); document.write( "\"+%28+r+-+2%2F5+%29%2A%28+r+-+1%2F5+%29+=+0+\" ( I could see the result by inspection )
\n" ); document.write( "\"+r+=+2%2F5+\" and
\n" ); document.write( "\"+r+=+1%2F5+\" are the solutions
\n" ); document.write( "But here's solution by completing the square:
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+=+-2%2F25+\"
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+%283%2F10%29%5E2+=+-2%2F25+%2B+%283%2F10%29%5E2+\"
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+9%2F100+=+-2%2F25+%2B+9%2F100+\"
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+9%2F100+=+-8%2F100+%2B+9%2F100+\"
\n" ); document.write( "\"+r%5E2+-+%283%2F5%29%2Ar+%2B+9%2F100+=+1%2F100+\"
\n" ); document.write( "\"+%28+r+-+3%2F10+%29%5E2+=+%281%2F10%29%5E2+\"
\n" ); document.write( "take the square root of both sides
\n" ); document.write( "\"+r+-+3%2F10+=+1%2F10+\"
\n" ); document.write( "\"+r+=+4%2F10+\"
\n" ); document.write( "\"+r+=+2%2F5+\"
\n" ); document.write( "But, also I can say that
\n" ); document.write( "\"+r+-+3%2F10+=+-1%2F10+\"
\n" ); document.write( "Taking the negative square root of (1/10)^2
\n" ); document.write( "\"+r+=+3%2F10+-+1%2F10+\"
\n" ); document.write( "\"+r+=+2%2F10+\"
\n" ); document.write( "\"+r+=+1%2F5+\"
\n" ); document.write( "I get the same answers
\n" ); document.write( "I hope this helps\r
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