Question

hello
i think this is a very challenging problem

suppose a,b,c are possitive numbers such that a+b+c=1, the the maximum value of ab+bc+ca is ???

Answer 1

it have somo answer choices 1/3 , 1/4 , 1/2 , 2/3

Answer 2

It is so hard that no one can answer it

Answer 3

for you to attain the maximum value, a must be equal to b and c
a=b=c
then you can express
a + b + c = 1 as
a + a + a = 1
3a = 1
a = 1/3
now you try to substitute that value to find ab + bc + ca

Answer 4

Oh maybe it isn't that hard...