document.write( "Question 355091: im really stuck on this question\r
\n" ); document.write( "\n" ); document.write( "the roots of the quadratic equation x^2 + 4x - a= 0 are b+1 and b-3. Find the values of a and b.
\n" ); document.write( "thnks :) \r
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Algebra.Com's Answer #253613 by jsmallt9(3758)\"\" \"About 
You can put this solution on YOUR website!
One form of a quadratic equation is:
\n" ); document.write( "\"%28x+-+r%5B1%5D%29%28x+-+r%5B2%5D%29+=+0\"
\n" ); document.write( "In this form \"r%5B1%5D\" and \"r%5B2%5D\" are the two roots of the quadratic equation. This is the form which is often used when solving quadratic equations.

\n" ); document.write( "So you equation, with its roots of b+1 and b-3, can be written in the form:
\n" ); document.write( "\"%28x+-+%28b%2B1%29%29%28x+-+%28b-3%29%29+=+0\"
\n" ); document.write( "which simplifies to:
\n" ); document.write( "\"%28x+-+b+-+1%29%28x+-+b+%2B+3%29+=+0\"
\n" ); document.write( "Multiplying this out (multiplying each term of one factor by each term of the other) we get:
\n" ); document.write( "\"x%5E2+-bx+%2B+3x+-bx+%2B+b%5E2+-3b+-x+%2Bb+-+3+=+0\"
\n" ); document.write( "Combining like terms we get:
\n" ); document.write( "\"x%5E2+-2bx+%2B+2x+%2B+b%5E2+-2b+-+3+=+0\"
\n" ); document.write( "Then, for reasons that should be clear soon, I'll factor out the x from -2bx + 2x and also group the constant terms (the terms with no \"x\"):
\n" ); document.write( "\"x%5E2+%2B+%28-2b+%2B+2%29x+%2B+%28b%5E2+-2b+-+3%29+=+0\"
\n" ); document.write( "In order for this equation to be the same as:
\n" ); document.write( "\"x%5E2+%2B+4x+-+a=+0\"
\n" ); document.write( "then the coefficients of the x terms must be the same:
\n" ); document.write( "-2b + 2 = 4
\n" ); document.write( "and the constant terms must be the same:
\n" ); document.write( "\"b%5E2+-2b+-+3+=+-a\"
\n" ); document.write( "(The \"x%5E2\" terms are already the same.) From
\n" ); document.write( "-2b + 2 = 4
\n" ); document.write( "we can solve for b:
\n" ); document.write( "-2b = 2
\n" ); document.write( "b = -1
\n" ); document.write( "Then we can use this and the equation \"b%5E2+-2b+-+3+=+a\" to find a:
\n" ); document.write( "\"%28-1%29%5E2+-2%28-1%29+-+3+=+-a\"
\n" ); document.write( "\"1+-2%28-1%29+-+3+=+-a\"
\n" ); document.write( "\"1+%2B2+-+3+=+-a\"
\n" ); document.write( "\"0+=+-a\"
\n" ); document.write( "\"0+=+a\"
\n" ); document.write( "So a = 0 and b = -1 and your equation was \"x%5E2+%2B+4x+=+0\"
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