Question

a+1/a=7, then find tge value of a+1/a whole power 7 ?

Answer 1

18

a+1/a = 3. eq(1)

taking cube on both sides then eq(1) becomes

(a+1/a)^3 = 3^3

by using the formula

[ (a + b)^3 = a3 + 3ab(a+b) + b3 ]

a3 + 3(a)(1/a)(a+1/a) + (1/a)^3 = 9

a3 + b3 +(a+1/a) = 9

As we know that. (a+1/a)= 3

so,

a3 + 1/a3 +3(3) = 9

a3 +1/a3 + 9 = 9

a3+1/a3 = 9-9

a3+1/a3 = 0 ✓✓ [SOLVED]

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