Need help with differentiation

Thread starter 4 months ago
#1
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4 months ago
#2
(Original post by Matheen1)
What have you done so far?
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Thread starter 4 months ago
#3
(Original post by davros)
What have you done so far?
I worked out dy/dx and made it equal to zero
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4 months ago
#4
(Original post by Matheen1)
I worked out dy/dx and made it equal to zero
You need to work out the second derivative and see what that tells you.
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Thread starter 4 months ago
#5
(Original post by Bronfenbrennerzy)
You need to work out the second derivative and see what that tells you.
I got stuck on finding dy/dx
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4 months ago
#6
(Original post by Matheen1)
I got stuck on finding dy/dx
It's pretty straightforward, differentiate y = 2x^2 - x^1/2 with respect to x. To differentiate, you multiply the number at the front of x with the exponent and then decrease the exponent by 1.
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4 months ago
#7
(Original post by Matheen1)
stationary points is when dy/dx = 0 right

so first i would differentiate the equation

then set dy/dx = 0

u should only get one answer

which is ur stationary point

that x that u found, sub in original equation to get y and there u go!
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3 months ago
#8
(Original post by Parinoor)
stationary points is when dy/dx = 0 right

so first i would differentiate the equation

then set dy/dx = 0

u should only get one answer

which is ur stationary point

that x that u found, sub in original equation to get y and there u go!
That's not sufficient to prove that it's a minimum though
1
3 months ago
#9
(Original post by Matheen1)
I worked out dy/dx and made it equal to zero
Do you know how to find the nature of a stationary point?
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3 months ago
#10
(Original post by IJaguar)
Do you know how to find the nature of a stationary point?
Check by substituting example x values just slightly above and below the point:-

If value of y is sl lower just below and sl lower just above, it is a max

If both sl higher, then min.

If both in same direction, then inflexion point.

You can work out why - I know you believe in using your brain from the bio Q a few min ago!!
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