- #1
FelixHelix
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I'm confused with a question and wondered if anyone could help explain where I need to go...
let x ε R. Prove that x is irrational thenI'm confused with a question and wondered if anyone could help explain where I need to go...
let x ε R. Prove that x is irrational then ((5*x^(1/3))-2)/7) is irrational.
I've learned that this is a proof by contrapositive so set ((5*x^(1/3))-2)/7) to be rational and hence a/b with a,b ε Z and b ≠ 0, and there for x is rational.
But I'm not sure where to go from here. Do I rearrange to find for x? x = ((7a - 10b)/5b)^3
But this is still raational isn't it? Where is the contradiction?
Thanks
let x ε R. Prove that x is irrational thenI'm confused with a question and wondered if anyone could help explain where I need to go...
let x ε R. Prove that x is irrational then ((5*x^(1/3))-2)/7) is irrational.
I've learned that this is a proof by contrapositive so set ((5*x^(1/3))-2)/7) to be rational and hence a/b with a,b ε Z and b ≠ 0, and there for x is rational.
But I'm not sure where to go from here. Do I rearrange to find for x? x = ((7a - 10b)/5b)^3
But this is still raational isn't it? Where is the contradiction?
Thanks