The maximum slope of the curve y = 1 2 x 4 - 5 x 3 + 18 x 2 - 19 x occurs at the point

The maximum slope of the curve y=12x4-5x3+18x2-19x occurs at the point
  1. 3,212
  2. 2,2
  3. 2,9
  4. 0,0

Solution

dydx=2x3-15x2+36x-19

Since, slope is maximum so,

d2ydx2=6x2-30x+36=0

x2-5x+6=0

x=2,3

at x=2

d3ydx3=12x-30

at x=2,d3ydx3<0

So, maxima

y=12×16-5×8+18×4-19×2

=8-40+72-38=80-78=2

point 2,2

Asked in: JEE Main 2021 (26 Feb Shift 1)

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