Q). Let a,b,c be the roots of x^3 + 2x^2 + 7x + 1 = 0.

Obtain A^3 +b^3 +C^3

SOLUTION).

a + b + c = -2

ab + bc + ca = 7

abc = -1

Now what is (a + b+ c)^3 = a^3 + b^3 + c^3 ++++++++

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- Aug 23rd 2008, 01:16 AMpuneetcubic formula
Q). Let a,b,c be the roots of x^3 + 2x^2 + 7x + 1 = 0.

Obtain A^3 +b^3 +C^3

SOLUTION).

a + b + c = -2

ab + bc + ca = 7

abc = -1

Now what is (a + b+ c)^3 = a^3 + b^3 + c^3 ++++++++ - Aug 23rd 2008, 01:44 AMMoo
- Aug 23rd 2008, 02:18 AMpuneetsolution
a^3 +b^3 +c^3=(a+b+c)^3+3abc-3(a+b+c)(ab+bc+ca)

=(-2)^3 +3(-1) -3(-2)(7)

=-8-3+42

=31 ans

Is this right - Aug 23rd 2008, 02:22 AMMoo