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OpenStudy (anonymous):
find the values of x where the extreme values of the function y=x^3-7x-5x occur.
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OpenStudy (anonymous):
i hope this is calculus
OpenStudy (anonymous):
and i hope there is a typo there too
check the question, because it looks funny
OpenStudy (anonymous):
could it be \( y=x^3-7x^2-5x\) ?
OpenStudy (anonymous):
no there is no typo its like this in the book and the answers choice i get is not there
OpenStudy (anonymous):
probably a typo in the book then
why write \(x^3-7x-5x\) instead of \(x^3-12x\)
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OpenStudy (anonymous):
\[y=x^3-7x-5x\]
OpenStudy (anonymous):
then start with
\[y=x^3-12x\] making \[y'=3x^2-12\] and set that equal to zero and solve
OpenStudy (anonymous):
i get 2 and -2
but that is not my choices
OpenStudy (anonymous):
(a) x=-0.33, x=5
(b) x=0.33, x=-5
(c) x=0.33, x=5
(d) x=2, x=5
(e) x=0.65 ,x=7.65
OpenStudy (anonymous):
yeah so do i
that is why i think it is a typo
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OpenStudy (anonymous):
lets try
\[y=x^3-7x^2-5x\\
y'=3x^2-14x-5\\
y'=(3x+1)(x-5)\]
OpenStudy (anonymous):
then you get critical points at \(x=-\frac{1}{3},x=5\)
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