document.write( "Question 951590: Write an equation for the parabola in standard form with a vertex of (-1, -2) \n" ); document.write( "
Algebra.Com's Answer #581137 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
If the form of the equation is:
\n" ); document.write( "\"+y+=+a%2Ax%5E2+%2B+b%2Ax+%2B+c+\"
\n" ); document.write( "\"+x%5Bv%5D+=+-b%2F%282a%29+\"
\n" ); document.write( "Vertex = ( -1,-2 )
\n" ); document.write( "\"+-1+=+-b%2F%282a%29+\"
\n" ); document.write( "\"+b+=+2a+\"
\n" ); document.write( "-------------
\n" ); document.write( "Now I can say:
\n" ); document.write( "\"+y+=+a%2Ax%5E2+%2B+2a%2Ax+%2B+c+\"
\n" ); document.write( "and, since ( -1,-2 ) is a solution:
\n" ); document.write( "\"+-2+=+a%2A%28-1%29%5E2+%2B+2a%2A%28-1%29+%2B+c+\"
\n" ); document.write( "I'll say \"+c+=+0+\" for this parabola
\n" ); document.write( "\"+-2+=+a%2A%28-1%29%5E2+%2B+2a%2A%28-1%29+%2B+0+\"
\n" ); document.write( "\"+-2+=+a+-+2a+\"
\n" ); document.write( "\"+-a+=+-2+\"
\n" ); document.write( "\"+a+=+2+\"
\n" ); document.write( "and
\n" ); document.write( "\"+b+=+2a+\"
\n" ); document.write( "\"+b+=+4+\"
\n" ); document.write( "------------
\n" ); document.write( "So, the equation is:
\n" ); document.write( "\"+y+=+2x%5E2+%2B+4x+\"
\n" ); document.write( "check:
\n" ); document.write( "Does it go through (-1,-2 )?
\n" ); document.write( "\"+-2+=+2%2A%28-1%29%5E2+%2B+4%2A%28-1%29+\"
\n" ); document.write( "\"+-2+=+2+-+4+\"
\n" ); document.write( "\"+-2+=+-2+\"
\n" ); document.write( "OK
\n" ); document.write( "Here's the plot:
\n" ); document.write( "\"+graph%28+400%2C+400%2C+-10%2C+10%2C+-10%2C+10%2C+2x%5E2+%2B+4x+%29+\"\r
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