Question

if a+b=10,ab=21.then a cube+b cube=

Answer 1

a³+b³=(a+b)³-3ab(a+b)
=(10)³-3*21*10
=1000-630
=370

Answer 2

a+b = 10 and ab = 21

a³+b³ = (a+b)³ - 3a²b-3ab²

→ (10)³ - 3ab(a+b)

→ 10³ - 3(21)(10)

→ 1000-630

→ 370

Hope it helps