Q. 64.3( 3 Votes )
You have seen that √2 is not a rational number. Show that
2 + √2 is not a rational number.
Answer :
Let 2 + √2be a rational number say r.
Then,2 + √2=r
√2=r - 2
But, √2is an irrational number.
LHS is irrational thus RHS should also be irrational to maintain the equality.
Therefore, r – 2 is also an irrational number
⇒ r is an irrational number.
Hence our assumption r is a rational number is wrong.
Hence, 2 + √2 is not a rational number.
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PREVIOUSWhich of the following rational numbers have the terminating decimalrepresentation? (i)3/5 (ii)7/20 (iii)2/13 (iv) 27/40 (v)133/125 (vi)23/7 [Making use of the result that a rational number p/q where p and q have nocommon factor(s) will have a terminating representation if and only if theprime factors of q are 2's or 5's or both.NEXT Prove that Prove that3â3is not a rational number.
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