If x 3 y 3 91 and x y 7 then find the value of 1 x 1 y ........

Quantitative Aptitude (CDS) Simplification

If x^3 +y^3 =91 and x+y =7 ,then find the value of 1/x +1/y ?

7/12

3/7

x^3+y^3=91
=(x +y)^3 -3xy(x+y)=91
=7^3 -3xy(7)=91
=-21xy=91-343
=-21xy =-252
=xy=12
=x+y/xy =7/12
=1/x +1/y =7/12

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