Question

Expand: (3a + b + 2c)^2

Answer 1

Answer:

using (a+b+c)^2 = a^2 + b^2 + c^2 + 2ab + 2bc + 2ca

(3a + b + 2c)^2

9a^2 + b^2 + 4c^2 + 2(3a*b) + 2(b*2c) +2(2c*3a)

9a^2 + b^2 + 4c^2 + 6ab + 4bc + 12ca