document.write( "Question 1027573: Let f be a function such that f(0) = 2 and f'(x)<=6 for -10<=x<=10.\r
\n" ); document.write( "\n" ); document.write( "A) What is the maximum possible value of f(4)?
\n" ); document.write( "B) What is the maximum possible value of f(2)?
\n" ); document.write( "C) Can f(5) be negative? Can f(5) = 0? Why or Why not?
\n" ); document.write( "D) Can f(5) = 31? Can f(5) = 35? Why or why not?
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Algebra.Com's Answer #642786 by robertb(5830)\"\" \"About 
You can put this solution on YOUR website!
By the mean value theorem,\r
\n" ); document.write( "\n" ); document.write( "there is a \"0%3C=+alpha+%3C=+x\" such that \"f%28x%29+=+f%280%29+%2B+%28df%28alpha%29%2Fdx%29x\"\r
\n" ); document.write( "\n" ); document.write( "==> \"f%28x%29+%3C=+f%280%29+%2B+6x+=+2+=+6x\" because \"df%28x%29%2Fdx+%3C=+6\" for all x in [-10,10].\r
\n" ); document.write( "\n" ); document.write( "A) ==> \"f%284%29+%3C=+2+%2B+6%2A4+=+26\" ==> maximum possible value of f(4) is 26.\r
\n" ); document.write( "\n" ); document.write( "B) ==> \"f%282%29+%3C=+2+%2B+6%2A2+=+14\" ==> maximum possible value of f(2) is 14.\r
\n" ); document.write( "\n" ); document.write( "C) Can f(5) be negative? YES. The derivative in the neighborhood around x = 5 can be negative enough (and hence the graph fall drastically enough) so as to warrant the graph of of f(x) to cross the x-axis before x = 5. (Remember, f'(x) is less than or equal to 6 in [-10,10].)\r
\n" ); document.write( "\n" ); document.write( "Can f(5) = 0? YES, by a reasoning very similar to the preceding paragraph.\r
\n" ); document.write( "\n" ); document.write( "D) Can f(5) = 31? YES.
\n" ); document.write( "\"f%285%29+%3C=+2+%2B+6%2A5+=+32\" ==> maximum possible value of f(5) is 32.\r
\n" ); document.write( "\n" ); document.write( "Can f(5) = 35? NO. The highest f(5) can get is 32
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