1.

If x+1 upon x is equal to 7 then what will be the value of x+1 upon x whole raised to 3

Answer»

x+1/x=7 → (1)

SQUARING both sides

x²+1/x²+2=49

x²+1/x²=47 → (2)

MULTIPLY (1) and (2)

x³+1/x³+1+1/x=329

x³+1/x³+7=329

x³+1/x³=322

Now,

(x+1/x)³=x³+1/x³+3(x+1/x)

          =322+3(7)

          =322+21

          =343



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