Let x = y^(1/3)
x^2 - 9x + 8 = 0
(x - 8)(x - 1) = 0
x = 8 or 1
y^(1/3) = 8 or 1
y = 2 or 1
2006-11-26 13:42:39
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answer #1
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answered by Texas Cowgirl 3
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Well the tricky part is that it is a cube root. eliminate that by mulitplying by all numbers with ^3 exponential.
y^(2/3)3 - 9y(1/3)3 + 8^3 = 0
it becomes y^2 - 9y + 512 = 0
therefore solve the quadratic equation. hope that helps.
2006-11-26 21:51:52
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answer #2
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answered by radtadstar 2
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y^(2/3) - 9y^(1/3) + 8 = 0
multiply everything times the 3rd exponent
so you would get y^2 - 9y + 8^3 = 0
and now use quadratric equation
2006-11-26 21:52:36
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answer #3
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answered by Anonymous
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You make a substitution for y. let z=y^1/3; then your equation becomes z^2 - 9*z + 8 = 0. This is a simple quadratic you can slove for z; then y will = z^3 to get the final results
2006-11-26 21:42:11
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answer #4
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answered by gp4rts 7
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Let x=y^(1/3), and set the equation in terms of x. It will be quadratic, x^2 + bx + c, for some b and c, which may be positive or negative. Solve for x. Cube that, and you get y.
Finally, check in the original equation.
2006-11-26 21:42:02
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answer #5
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answered by Anonymous
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