Question

If a+b+c = 9
and ab+bc+ca=26
Find the value of a^3 + b^3 +c^3 -3abc

Pls I need answer

Answer 1

Answer:

Given, a+b+c=9 and ab+bc+ca=26.

We know, (a+b+c)

2

=a

2

+b

2

+c

2

+2ab+2bc+2ca

⇒(a+b+c)

2

=a

2

+b

2

+c

2

+2(ab+bc+ca).

Putting the values here, we get,

(9)

2

=a

2

+b

2

+c

2

+2(26)

⇒81=a

2

+b

2

+c

2

+52

⇒a

2

+b

2

+c

2

=81−52=29.

Hence, option D is correct.