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Determine the derivative, all the critical numbers and the intervals of increase and decrease
y=5x²+20x+2
 10 months ago
 10 months ago
Determine the derivative, all the critical numbers and the intervals of increase and decrease y=5x²+20x+2
 10 months ago
 10 months ago

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burhan101Best ResponseYou've already chosen the best response.0
\[\huge y'=10x+20\] \[\huge 0=10x+20\] \[x=2\]
 10 months ago

burhan101Best 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
 10 months ago

Abhishek619Best ResponseYou've already chosen the best response.0
when \[y \prime >0, \] then increasing.
 10 months ago

burhan101Best ResponseYou've already chosen the best response.0
what's in intervals of increase / decrease tho?
 10 months ago

koymoiBest 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
 10 months ago

Abhishek619Best ResponseYou've already chosen the best response.0
x>2 it decreases x<2 it increases.
 10 months ago

johnweldon1993Best ResponseYou've already chosen the best response.0
Right...I as well @koymoi ...I think maybe your answer key is wrong @burhan101
 10 months ago

burhan101Best ResponseYou've already chosen the best response.0
think the answer key's wrong then ?
 10 months ago

burhan101Best ResponseYou've already chosen the best response.0
yeah, i thought it was a fairly straight forward question
 10 months ago

dan815Best ResponseYou've already chosen the best response.0
graph it and ull know for sure
 10 months ago

dan815Best ResponseYou've already chosen the best response.0
oh oops that shud be + when i multiplied by 5
 10 months ago

genius12Best 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 \(\bf (2,\infty)\)
 10 months ago
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