Question

a + b + c = 6, a²+b²+c²=14 then ab+bc+can=?​

Answer 1

Answer:

11

We know that (a + b + c)^2 = a^2 + b^2 + c^2 + 2 (ab + bc + ca)

We know that (a + b + c)^2 = a^2 + b^2 + c^2 + 2 (ab + bc + ca)⇒ 62 = 14 + 2 (ab + bc + ca)

We know that (a + b + c)^2 = a^2 + b^2 + c^2 + 2 (ab + bc + ca)⇒ 62 = 14 + 2 (ab + bc + ca)⇒ (36 - 14)/2 = (ab + bc + ca)

We know that (a + b + c)^2 = a^2 + b^2 + c^2 + 2 (ab + bc + ca)⇒ 62 = 14 + 2 (ab + bc + ca)⇒ (36 - 14)/2 = (ab + bc + ca)⇒ ab + bc + ca = 11