Question

a+b+c=9and a square +b square +c square =29 find ab+bc+ca​

Answer 1

Answer:

ab + bc + ca = 26

Step-by-step explanation:

Given,

a + b + c = 9

a^2 + b^2 + c^2 = 29

To find : ab + bc + ca = ?

​( a + b + c )^2 = 9^2

​( a + b + c )^2 = a^2 + b^2 + c^2 + 2 ( ab + bc + ca )   { formula / identity }

9^2 = 29 + 2 ( ab + bc + ca )

81 = 29 + 2 ( ab + bc + ca )

81 - 29 = 2 ( ab + bc + ca )

52 = 2 ( ab + bc + ca )

ab + bc + ca = 52 / 2

ab + bc + ca = 26