Question 508207
3y^2/3+21y^1/3+30=0 
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Quadratic Form with variable y^(1/3).
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Let w = y^(1/3) to get:
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3w^2 + 21w + 30 = 0
3[w^2+7w+10] = 0
(w+5)(w+2) = 0
w = -5 or w = -2

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Now solve for y:
y^(1/3) = -5 or y^(1/3) = -2
y = -125 or y = -8
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Cheers,
Stan H.