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    (b) (i) Solve the equation y2 + 8 = 9y.

    (ii) Hence solve the equation x3 + 8 = 9x3/2 .

    I've managed to do part (i) but how on Earth do you do part (ii)? I've never been taught how to factorise or solve equations with fractional powers.
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    (Original post by jessyjellytot14)
    (b) (i) Solve the equation y2 + 8 = 9y.

    (ii) Hence solve the equation x3 + 8 = 9x3/2 .

    I've managed to do part (i) but how on Earth do you do part (ii)? I've never been taught how to factorise or solve equations with fractional powers.
    Part (i) is just a quadratic and you should be spotting the similarity between those two parts, look at how the numbers join up.

    In fact, if you use the substitution u = x^{3/2} you'll get u^2 + 8 = 9u which is precisely what you solved in the first part; so you need only back-substitute now.
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    (Original post by jessyjellytot14)
    (b) (i) Solve the equation y2 + 8 = 9y.

    (ii) Hence solve the equation x3 + 8 = 9x3/2 .

    I've managed to do part (i) but how on Earth do you do part (ii)? I've never been taught how to factorise or solve equations with fractional powers.
    Hint: Let y=x^{3/2}.

    EDIT: Too slow.
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    (Original post by jessyjellytot14)
    (b) (i) Solve the equation y2 + 8 = 9y.

    (ii) Hence solve the equation x3 + 8 = 9x3/2 .

    I've managed to do part (i) but how on Earth do you do part (ii)? I've never been taught how to factorise or solve equations with fractional powers.
    You can see in equation (ii) that 3/2 * 2 = 3. I.e., one term has double the exponent of the other, hence the similarity to equation (i)
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    (Original post by Zacken)
    Part (i) is just a quadratic and you should be spotting the similarity between those two parts, look at how the numbers join up.

    In fact, if you use the substitution u = x^{3/2} you'll get u^2 + 8 = 9u which is precisely what you solved in the first part; so you need only back-substitute now.
    (Original post by Farhan.Hanif93)
    Hint: Let y=x^{3/2}.

    EDIT: Too slow.
    (Original post by oShahpo)
    You can see in equation (ii) that 3/2 * 2 = 3. I.e., one term has double the exponent of the other, hence the similarity to equation (i)
    Oooh okay thanks, i'll give it go
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    (Original post by jessyjellytot14)
    Oooh okay thanks, i'll give it go
    No problem, let us know how you get on.
 
 
 
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