Question

a+b=3 and ab=-4,a³+b³=?​

Answer 1

Using this formulae, a³ + b³ = (a + b)³ + 3ab(a + b)

Solution :-

We have values a + b = 3 and ab = -4.

So, now put value in formulae, we get

a³ + b³ = (a + b)³ + 3ab(a + b)

= 3³ + 3 × (-4) × 3

= 27 + (-36)

a³ + b³ = -9

∴ The answer is -9.