Question

$if \: (x {}^{2} + 1 \div x {}^{2} ) = 7 \: find \: value \: of(x {}^{3} + 1 \div x {}^{3} )$
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Answer 1

Answer:

x^2+1/x^2=7

x^3+1/x^3=

x^2+1/x^2=(x+1/x)^2-2

x+1/x=7+2=9

x^3+1/x^3

is in the form a^3+b^3=(a+b)(a^2-ab+b^2)

so

(x+1/x)(x^2+1/x^2-1)

(9)(7-1)

(9)(6)=54