document.write( "Question 397766: Hai sir, please help me on this problem\r
\n" ); document.write( "\n" ); document.write( "\"Determine all inflection points of function f defined by, f(x) = x4 + x3 + 2
\n" ); document.write( "a)(0,1) and (1/2, 15/31)
\n" ); document.write( " b)(0,1) and (1/3, 12/32)
\n" ); document.write( " c)(0, 2) and ( -1/2, 31/16)
\n" ); document.write( " d)None of these
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Algebra.Com's Answer #281820 by robertb(5830)\"\" \"About 
You can put this solution on YOUR website!
\"df%2Fdx++=4x%5E3+%2B+3x%5E2\" ==> \"d%5E2f%2Fdx%5E2+=+12x%5E2+%2B+6x+\".
\n" ); document.write( "Set the 2nd derivative to 0:\r
\n" ); document.write( "\n" ); document.write( " \"d%5E2f%2Fdx%5E2+=+12x%5E2+%2B+6x++=+6x%282x+%2B+1%29+=+0\" ==> x = 0, -1/2.
\n" ); document.write( "When x = -1, \"d%5E2f%2Fdx%5E2+%3E+0\",
\n" ); document.write( "when x = -1/4, \"d%5E2f%2Fdx%5E2+%3C+0\", and
\n" ); document.write( "when x = 1, \"d%5E2f%2Fdx%5E2+%3E+0\".
\n" ); document.write( "Therefore there are changes of concavity in the intervals (\"-infinity\", -1/2), (-1/2, 0), and (0, \"infinity\"). To find the y-coordinates, substitute x = 0 and x = -1/2 in to original function.\r
\n" ); document.write( "\n" ); document.write( "The answer is c.
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