Question

If a + b+ c = 9 and ab + bc + ca = 26, find a2 + b2 + c2.​

Answer 1

9514 1404 393

Answer:

  29

Step-by-step explanation:

We can use ...

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

  9² = a² +b² +c² +2(26)

  a² +b² +c² = 81 -52 = 29

Answer 2

Step-by-step explanation:

We know the formula:

(a+b+c)² = a² + b² + c² + 2(ab+bc+ca)

Given:

a+b+c = 9 & ab+bc+ca = 26

Now putting the values in the above formula,

We get,

(9)² = a² + b² + c² + 2×26

81 = (a² +b² +c²) + 52

(a² +b²+c²) = 81-52

(a² + b² + c²) = 29 (Answer)