Question

please answer the 14th question!! thank you so much :D

Answer 1

Step-by-step explanation:

a²+b²+c²-ab -bc - ca = {(a-b)² +(b-c)² + (c-a)²}/2

Now here , it is the sum of squares .

Squares are always equal to zero or are +ve.

This expression will be equal to zero when a = b = c or will be positive .

Hence ,

a² + b² + c² - ab - bc - ca is always non-negative.

Hence proved.