Question

if a+b+c=5 and ab+bc+ac=9 find the value of a^3+b^3+c^3
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Answer 1

Answer:

-20

Step-by-step explanation:

A+B+C= 5

AB+BC+CA=9

We know ,

a³ + b³ + c³ -3abc = (a + b + c )(a² + b² + c² -ab -bc-ca)

now ,

a + b + c = 5

ab + bc + ca = 9

(a + b + c)² = a² + b² + c² +2(ab + bc+ca)

(5)² -2×9 = a² + b² + c²

a² + b² + c² =3

hence ,

a³ + b³ +c³ -3abc = ( a + b + c )(a² + b² + c² -ab- bc-ca)

=( 5)( 5 - 9) = 5 × (-4)

= -20

Hope this will help u.....