document.write( "Question 360030: It has a vertex at(-1,-1) and passes the point(0,0) . Find the quadratic function. f(x)=
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Algebra.Com's Answer #256873 by robertb(5830) $\"\"$ $\"About$

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The vertex form of the parabola is $\"y+=+a%28x-h%29%5E2%2Bk\"$ , where(h,k) is the vertex of the parabola. By direct substitution, $\"y+=+a%28x--1%29%5E2-1\"$ , or
\n" ); document.write( " $\"y+=+a%28x%2B1%29%5E2-1\"$ . We use the coordinates of the origin (0,0) to solve for a:
\n" ); document.write( " $\"0+=+a%280%2B1%29%5E2-1\"$ , or
\n" ); document.write( " $\"0+=+a-1\"$ , or $\"a+=+1\"$ .
\n" ); document.write( "Therefore the function is $\"f%28x%29+=+%28x%2B1%29%5E2-1\"$ , or $\"f%28x%29+=+x%5E2%2B2x\"$ . \n" ); document.write( "

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