document.write( "Question 530685: find the vertex of the parabola y = -4x2 - 16x - 11 \n" ); document.write( "

Algebra.Com's Answer #350192 by Earlsdon(6294) $\"\"$ $\"About$

You can put this solution on YOUR website!
The x-coordinate of the vertex can be found by:
\n" ); document.write( " $\"x+=+%28-b%29%2F2a\"$ where: a = -4 and b = -16.
\n" ); document.write( " $\"x+=+%28-%28-16%29%29%2F2%28-4%29\"$ Evaluate.
\n" ); document.write( " $\"x+=+16%2F%28-8%29\"$
\n" ); document.write( " $\"x+=+-2\"$ Now substitute this value of x into the given quadratic equation to find the value of the y-coordinate.
\n" ); document.write( " $\"y+=+-4%28-2%5E2%29-16%28-2%29-11\"$ Evaluate.
\n" ); document.write( " $\"y+=+-16%2B32-11\"$
\n" ); document.write( " $\"y+=+5\"$
\n" ); document.write( "The vertex is at (-2,5)
\n" ); document.write( "Here's the graph:
\n" ); document.write( " $\"graph%28400%2C400%2C-5%2C5%2C-5%2C10%2C-4x%5E2-16x-11%29\"$ \n" ); document.write( "

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