document.write( "Question 37236: Create the quadratic equation in the form ax squared + bx + c using the point
\n" ); document.write( "(-1,7) as one point and the point (10,-8) as the vertex. enter a,b,c values as common fractions in reduced form. \r
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\n" ); document.write( "\n" ); document.write( "i have several problems just like this to answer. i need to know how to come up with the equation. please help. cheryl mitchell clm031303@yahoo.com \n" ); document.write( "
Algebra.Com's Answer #22921 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
Create the quadratic equation in the form ax squared + bx + c using the point
\n" ); document.write( "(-1,7) as one point and the point (10,-8) as the vertex. enter a,b,c values as common fractions in reduced form. \r
\n" ); document.write( "\n" ); document.write( "Because the vertex is (10,-8),
\n" ); document.write( "-b/2a=10
\n" ); document.write( "Then b=-20a
\n" ); document.write( "Rewrite the equation as follows:
\n" ); document.write( "y=ax^2-20ax+c
\n" ); document.write( "Using the point (-1,7) you get:
\n" ); document.write( "7=a+20a+c
\n" ); document.write( "Using the point (10,-8) you get:
\n" ); document.write( "-8=100a-200a+c
\n" ); document.write( "Rewriting both of these you get two equations in a and c, as follows:
\n" ); document.write( "7=21a+c
\n" ); document.write( "-8=-100+c
\n" ); document.write( "Subtracting the 1st from the 2nd you get:
\n" ); document.write( "15=121a or a=15/121
\n" ); document.write( "Substituting that back you can solve for c which is c=532/121
\n" ); document.write( "Substituting back into y=ax^2-20ax+c you get the equation you want:
\n" ); document.write( "y=(15/121)x^2-(300/121)x+(532/121)
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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