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Algebra/d^2y/dx^2 = 2 which is positive...

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Question
d^2y/dx^2 = 2 which is positive hence the turning point is a minimum,

can you find the turning points for the following curves and distinguish between them ?
a) x = 0(6-0)
b) x = 8t + 1/2t^2

(the ''0'' in question a) has a horizontal line through the middle)


Answer
a) I'll use 't' instead of '0'...so, x=t(6-t)=6t-t^2
  dx/dt=6-2t=0 ==> t=3, with x''=-2, thus t=3
  corresponds to a maximum (esp. since the graph is
  an upside-down parabola)!

b) x'=8+t=0 ==> t=-8, with x''=1...thus t=-8 corresponds
  to a minimum (esp. since the graph is parabola)!

Abe

Algebra

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Abe Mantell

Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

Experience

Over 15 years teaching at the college level.

Organizations
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook

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