Question

Expand: (2a + 3b + 4c)²​

Answer 1

$\huge\underline\mathfrak\red{Solution}$

→ (2a + 3b + 4c)²

[putting 2a = x, 3b = y & 4c = z, we get]

→ (2a + 3b + 4c)²

= ( x + y + z)²

= x² + y² + z² + 2xy + 2yz + 2zx

= (2a)² + (3b)² + (4c)² + {2 × (2a) × (3b)} + {2 × (3b) × (4c)} + {2 × (4c) × (2a)}

= 4a² + 9b² + 16c² + 12ab + 24bc + 16ca

$\huge\mathbb\blue{THANK\:YUH!}$

Answer 2

Note: (a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ca

Given: (2a + 3b + 4c)²

=> (2a)² + (3b)² + (4c)² + 2(2a)(3b) + 2(3b)(4c) + 2(4c)(2a)

=> 4a² + 9b² + 16c² + 12ab + 24bc + 16ca

Hope it helps!