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Question
If x=4^1/3+4^-1/3 then find the value of 4x^3-12x.
tried to rationalise the denominator and substituting the value of x. even used the cube formula but cannot get the answer which is 17
Hello Dolly,
I've got it, it's a bit long. You just have to be careful with laws of exponents. Do you get?
4x^3 = 3*4^4/3 + 3*4^2/3 + 17
If that's the case then all you have to do is substract 12x. Obtain a common denominator and simplify all terms carefully.
Let me know if/where you're still stuck.
Good luck,
David
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Answers by Expert:
David Montiel
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Over 8 years of private tutoring in Math and Physics. Five years as a Teaching Assistant in Physics.
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BSc in Chemical Engineering.
MSc in Chemical Physics.
PhD in Physics.
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