Question

if a=9+4 root 5 and b=1/a then find the value of a^3+b^3

Answer 1

Step-by-step explanation:

Given, a=9+4√5 & b=1/9+4√5

therefore ..b=1×9-4√5/9+4√5×9-4√5

b=9-4√5/81-80

b=9-4√5

now....

a^3+b^3= (9+4√5)^3+(9-4√5)^3

= 9^3 +4√5^3+3ab(a+b) +9^3-4√5^3-3ab(a-b)

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