a3+b3=
(a+b)(a2+b2−ab)
(a+b)3−3ab(a+b)
(a+b)3+3ab(a+b)
(a+b)(a2+b2+ab)
We know that (a+b)3=a3+b3+3ab(a+b)
⇒a3+b3=(a+b)3−3ab(a+b) ... (i)
⇒a3+b3=(a+b)3−3ab(a+b)=(a+b)[(a+b)2−3ab]
=(a+b)(a2+b2+2ab−3ab)
=(a+b)(a2+b2−ab) ... (ii)
Which of the following equation/s is/are correct? i)(a+b+c)2=a2+b2+c2−2(ab+bc+ca) ii)(a+b)3=a3+b3+3ab(a−b) iii)(a−b)3=a3−b3−3ab(a+b) iv)a2−b2=(a+b)(a−b)