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If a + b + c = 14 , ab + bc + ca = 47 and abc = 15 then find the value of a3+b3+c3a^3 + b^3 + c^3a3+b3+c3.​
Question

If a + b + c = 14 , ab + bc + ca = 47 and abc = 15 then find the value of a3+b3+c3a^3 + b^3 + c^3.​

A.

845

B.

825

C.

835

D.

815

Correct option is D

Given:

a + b + c = 14 , ab + bc + ca = 47 and abc = 15

Formula Used:

a3+b3+c33abc=(a+b+c)×[(a+b+c)23(ab+bc+ca)]a^3 + b^3 + c^3 - 3abc = (a + b + c) \times \left[ (a + b + c)^2 - 3(ab + bc + ca) \right]

Solution:

a3+b3+c33abc=14×[(14)23×47]=>a3+b3+c33×15=14×(196141)=>a3+b3+c3=14×(55)+45=>770+45=>815\begin{aligned}a^3 + b^3 + c^3 - 3abc &= 14 \times \left[ (14)^2 - 3 \times 47 \right] \\&\Rightarrow a^3 + b^3 + c^3 - 3 \times 15 = 14 \times (196 - 141) \\&\Rightarrow a^3 + b^3 + c^3 = 14 \times (55) + 45 \\&\Rightarrow 770 + 45 \\&\Rightarrow 815\end{aligned}

Hence, option (d) is the correct answer.

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