Prove that √2-3√5 is an irrational number?
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Answer:
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Step-by-step explanation:
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TO PROVE:( 3 - 2√5) is irrational
For proving this , we can apply the theorem “ √5 is an irrational number”
PROOF: Let (3 - √5 ) be a rational number.
=> 3+√5= p/q ( where, p & q are integers, ‘q’ not = 0 )
=> √5 = (p/q) +3
=> √5 = (p+3q)/q
Here, in RHS , numerator is the difference of 2 integers, which always remains an integer. & denominator is also an integer, not = 0.
=> RHS is a rational number ( as, all the conditions for being a rational number, have been satisfied )
But LHS is an irrational number. ( by theorem, √5 is an irrational number)
=> LHS not = RHS
=> our assumption (that 3-√5 is a rational number) is wrong.
Hence, 3-√5 is an irrational number..