Question

If a+b+c= 0, by using the identity a³ + b³ + c³ = 3abc, find the value of (-28)³ + (15)³ + (13)³.

Answer 1

BONJOUR,
❤ ❤ ❤ ❤

$a + b + c = 0 \\ a {}^{3} + b {}^{3} + c {}^{3} = 3abc \\ then \\ ( - 28) {}^{3} + (15) {}^{3} + (13) {}^{3} \\ = 3 \times ( - 28) \times 15 \times 13 \\ - 16380 \\ hope \: it \: hepls$

Answer 2

Hi ,

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We know that ,

If a + b + c = 0 ,

Then a³ + b³ + c³ = 3abc

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Now ,

a = -28 ,

b = 15 ,

c = 13 ,

a + b + c = -28 + 15 + 13 = 0

Therefore ,

a³ + b³ + c³ = 3abc

=> ( - 28 )³ + 15³ + 13³

= 3 × ( -28 ) × 15 × 13

= - 16380

I hope this helps you.

: )