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burhan101
Group Title
Determine the derivative, all the critical numbers and the intervals of increase and decrease
y=5x²+20x+2
 one year ago
 one year ago
burhan101 Group Title
Determine the derivative, all the critical numbers and the intervals of increase and decrease y=5x²+20x+2
 one year ago
 one year ago

This Question is Closed

burhan101 Group TitleBest ResponseYou've already chosen the best response.0
\[\huge y'=10x+20\] \[\huge 0=10x+20\] \[x=2\]
 one year ago

burhan101 Group TitleBest ResponseYou've already chosen the best response.0
i get : intervals of increase x<2 intervals of decrease x>2 but the answer key says the opposite
 one year ago

Abhishek619 Group TitleBest ResponseYou've already chosen the best response.0
when \[y \prime >0, \] then increasing.
 one year ago

burhan101 Group TitleBest ResponseYou've already chosen the best response.0
what's in intervals of increase / decrease tho?
 one year ago

koymoi Group TitleBest ResponseYou've already chosen the best response.0
I got the same answer as you @burhan101 intervals of increase x<2 intervals of decrease x>2
 one year ago

Abhishek619 Group TitleBest ResponseYou've already chosen the best response.0
x>2 it decreases x<2 it increases.
 one year ago

johnweldon1993 Group TitleBest ResponseYou've already chosen the best response.0
Right...I as well @koymoi ...I think maybe your answer key is wrong @burhan101
 one year ago

burhan101 Group TitleBest ResponseYou've already chosen the best response.0
think the answer key's wrong then ?
 one year ago

burhan101 Group TitleBest ResponseYou've already chosen the best response.0
yeah, i thought it was a fairly straight forward question
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
graph it and ull know for sure
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
dw:1371791477746:dw
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
dw:1371791538467:dw
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
oh oops that shud be + when i multiplied by 5
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
dw:1371791697708:dw
 one year ago

dan815 Group TitleBest ResponseYou've already chosen the best response.0
dw:1371791721412:dw
 one year ago

genius12 Group TitleBest ResponseYou've already chosen the best response.1
@burhan101 u don't need calculus to find intervals of increase/decrease. This is a parabola with a negative leading coefficient so it opens down. Using b/2a we get b/2a = 2, which is the xcoordinate of the vertex of the parabola. Since it opens down, function is increasing on \(\bf (\infty,2)\) and decreasing on \(\bf (2,\infty)\)
 one year ago
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