1. (a + b + c)pangkat 2 ​

(a + b + c)²

= (a)² + (b)² + (c)²

= a² + b² + c²

Jwb :

= (a + b + c)²

= (a + b + c) × (a + b + c)

= (a × a) + (b × b) + (c × c)

= a² + b² + c²