Question

which expression DOES NOT represent a square root of a perfect square integer? A) 100 B) 64 C) 81 D) 89

Answer 1

Its 89 because 9 times 2 is 81 and 10 times 2 is 100 there nothing to multiple 2 by something to get 89

Answer 2

The answer is:  [D]:  "89" .
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Note:
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√100 = 10 ; 

√64  = 8 ;

√81  = 9 ; 

√89 = 9.4339811320566038 .
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