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    Given that y=x+ke^x where k is a constant, show that:
    (1-x)d^2y/dx^2 + x(dy/dx) - y = 0.

    where do i begin on this question??
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    (Original post by elvss567)
    Given that y=x+ke^x where k is a constant, show that:
    (1-x)d^2y/dx^2 + x(dy/dx) - y = 0.

    where do i begin on this question??
    Well, if y = x + ke^x then what's dy/dx? What's d^2y/dx^2?

    What's (1-x)d^2y/dx^2 + x(dy/dx) - y?
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    (Original post by Zacken)
    Well, if y = x + ke^x then what's dy/dx? What's d^2y/dx^2?

    What's (1-x)d^2y/dx^2 + x(dy/dx) - y?
    for dy/dx = 1 +ke^x
    d^2y/dx^2 = ke^x
    what do i do then?
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    (Original post by elvss567)
    for dy/dx = 1 +ke^x
    d^2y/dx^2 = ke^x
    what do i do then?
    You haven't answered my other question, but anyway:

    If dy/dx = 1 + ke^x and d^2y/dx^2 = ke^x then what's (1-x)d^2y/dx^2? What's x(dy/dx)? What's (1-x)d^2y/dx^2 + x(dy/dx) - y?
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    (Original post by Zacken)
    You haven't answered my other question, but anyway:

    If dy/dx = 1 + ke^x and d^2y/dx^2 = ke^x then what's (1-x)d^2y/dx^2? What's x(dy/dx)? What's (1-x)d^2y/dx^2 + x(dy/dx) - y?
    ohh so i'm just substituting in the equation for dy/dx and d2x/dy2 and y .
    then just simplifying it down?
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    (Original post by elvss567)
    ohh so i'm just substituting in the equation for dy/dx and d2x/dy2 and y .
    then just simplifying it down?
    yes
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    (Original post by Zacken)
    yes
    That makes so much more sense! Thankyou!
 
 
 
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