Question

Simplify: (a + b + c) (a + b – c).​

Answer 1

= (a + b + c) (a + b – c)

Identify used here is a² - b² = (a +b ) ( a - b)

= (a +b )² - c²

Use identify (a + b) ² = a² + 2ab + b²

= a² + 2ab + b² - c

Answer 2

Explanation:

( a+b+c) (a+b-c)

a(a+b-c) + b(a+b-c) + c(a+b-c)

a² + ab - ac + ab + b² - bc + ac + bc - c²

a² + b² - c² + 2ab