If x = 19 and y = 18, then the value of {x^{2}+y^{2}+x y}/{x^{3}-y^{3}} is

RRB RPF RPSF SI and CONS Model Papers 7 with solutions

Question : 39 of 120

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If x = 19 and y = 18, then the value of

{x^{2}+y^{2}+x y}/{x^{3}-y^{3}}

Solution:

(1) Expression

=\ {x^{2}+y^{2}+x y}/{x^{3}-y^{3}}

= {x^{2}+y^{2}+x y}/{(x-y) (x^{2}+y^{2}+x y )}

= {1}/ {x-y}

= {1}/{19-18}=1

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