Question

Expand (2-y)
If a + b = 9 and ab =20,then find the value of (a+b)3​

Answer 1

Question:-

If a + b = 9 and ab = 20 , then find the value of ( a + b )³

Solution:-

Identity => ( a + b )³ = a³ + b³ + 3ab( a + b )

Given :-

a + b = 9

ab = 9

We get ,

( a + b )³ = a³ + b³ + 3ab( a + b )

( 9 )³ = a³ + b³ + 3 × 20 ( 9)

729 = a³ + b³ + 60 × 9

729 = a³ + b³ + 540

a³ + b³ = 729 - 540

a³ + b³ = 189

Answer:- a³ + b³ = 189