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Confused with a fractional power

  • 20-04-2006 04:01PM
    #1
    Registered Users, Registered Users 2 Posts: 1,666 ✭✭✭


    This is just one part of a long ten term differentiation problem. Anyhow cutting out the bits I do have no problem with, is this little chap. I can't seem to find why this is happening back in my fractional power notes, and this is given as the solution to this particular part.

    -3/2x^3 = -3/2(x^-2)

    surely it should be = -3/2(x^-3)? If not, how come? Why the x^-2?

    Any ideas?

    Thanks.....


Comments

  • Closed Accounts Posts: 242 ✭✭planck2


    let y = x^n.
    I'm not sure if y = (-3/2)x^3 or -3/(2x^3). In anycase

    dy/dx = nx^(n-1)

    for example y =x^-1., dy/dx = -x^-2

    y= x^-2, dy/dx = -2x^-3.

    y = x^3, dy/dx = 3x^2

    y =x^(-1/2), dy/dx = (-1/2)x^(-3/2), this is called a fractional power


  • Registered Users, Registered Users 2 Posts: 1,666 ✭✭✭charlie_says


    planck2 wrote:
    let y = x^n.
    I'm not sure if y = (-3/2)x^3 or -3/(2x^3). In anycase

    dy/dx = nx^(n-1)

    for example y =x^-1., dy/dx = -x^-2

    y= x^-2, dy/dx = -2x^-3.

    y = x^3, dy/dx = 3x^2

    y =x^(-1/2), dy/dx = (-1/2)x^(-3/2), this is called a fractional power

    As it turns out it was a mistake by my tutor in the notes. Ho hum....

    Thanks anyway...


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