Question

Find the squares of the following: 
(2a + 3b - 4c)

Answer 1

Using (a + b + c)²
= a² + b² + c² + 2ab + 2bc + 2ac
(2a +3b - 4c)²
= (2a)² + (3b)² + (4c)² + 2(2a)(3b) + 2(3b)(-4c) + 2(2a)(-4c)
= 4a² + 9b² + 16c² + 12ab - 24bc - 8ac.