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Mathematics 6 Online
OpenStudy (anonymous):

How many local max/ min does P(x) = x^57 + 7x^11 + 3x - 1000 has?

OpenStudy (ghazi):

number of roots of first differentiation decides total number of minima and maxima , after one differentiation you will get highest order of 56 so it will have 56 roots and therefore total number is 56

OpenStudy (anonymous):

the answer is 0

OpenStudy (anonymous):

@ghazi answer is 0

OpenStudy (ghazi):

can you guess what could be the reason behind zero ?

OpenStudy (anonymous):

no.. something about (0, -1000)

OpenStudy (ghazi):

i am unable to think why it has answer zero , i don't think so , let me call my friend @mukushla buddy help

OpenStudy (ghazi):

@eliassaab sir, help

OpenStudy (anonymous):

haha

OpenStudy (anonymous):

hello because P(x) is a strictly increasing function since\[P'(x)=57x^{56}+77x^{10}+3>0\]

OpenStudy (ghazi):

@lovekblue why are you laughing bro lol

OpenStudy (ghazi):

there you go @lovekblue

OpenStudy (ghazi):

@mukushla sorry forgot this

OpenStudy (anonymous):

but P(x) starts from (0,-1000), wouldnt it cross 0 in some time?

OpenStudy (ghazi):

no, it would not it will tend to zero but won't cross zero

OpenStudy (anonymous):

how do u know o_o

OpenStudy (ghazi):

check out the definition that muku has mentioned above

OpenStudy (anonymous):

but what he talks about is P'(x)

OpenStudy (anonymous):

P'(x) is strictly increasing.. that doesnt help saying it wont cross 0...

OpenStudy (anonymous):

not P'(x) but P(x) is strictly increasing (why?) and P(x) is continous ...so there are no local Max or Min but there is a one root

OpenStudy (anonymous):

ohh right

OpenStudy (ghazi):

|dw:1352269291734:dw| think of something like this

OpenStudy (anonymous):

dont know why i suddenly related root to max/min.. i get it now thanks!

OpenStudy (anonymous):

np :)

OpenStudy (anonymous):

thanks both of u :)

OpenStudy (ghazi):

:) special thanks to @mukushla

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