document.write( "Question 798369: On what interval is the function f(x)=x^2-2x-9 increasing? \n" ); document.write( "

Algebra.Com's Answer #482173 by nerdybill(7384) $\"\"$ $\"About$

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On what interval is the function f(x)=x^2-2x-9 increasing?
\n" ); document.write( "we know that
\n" ); document.write( "f(x)=x^2-2x-9
\n" ); document.write( "is a \"quadratic\" (parabola)
\n" ); document.write( "we also know that it opens upwards (POSITIVE leading coefficient).
\n" ); document.write( "So, the \"increasing\" portion is the right side of the vertex.
\n" ); document.write( ".
\n" ); document.write( "Now we need the axis of symmetry or x-coordinate:
\n" ); document.write( "x = -b/(2a)
\n" ); document.write( "x = -(-2)/(2*1)
\n" ); document.write( "x = 2/(2)
\n" ); document.write( "x = 1
\n" ); document.write( ".
\n" ); document.write( "Therefore, the interval where the function is increasing (in interval notation):
\n" ); document.write( "(1, +oo)
\n" ); document.write( "where oo stands for infinity
\n" ); document.write( " \n" ); document.write( "

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