Question

if a+b=10 and ab=20, find the value of a^3+b^3

Answer 1

Answer :

Given that ;

a + b = 10

ab = 20

To find ;

( a³ + b³ )

Solution ;

a + b = 10

On cubing both sides ;

( a + b )³ = (10)³

⇒ a³ + b³ + 3ab( a + b ) = 1000

⇒ a³ + b³ + 3 * 20 ( 10 ) = 1000

⇒ a³ + b³ + 600 = 1000

⇒ a³ + b³ = 1000 - 600

⇒ a³ + b³ = 400

Hence, the answer is 400.

Answer 2

Answer:

400

Step-by-step explanation:

a^3+b^3 = (a+b)^3-3ab(a+b)

= 10^3-3*20*10

= 1000-600

=400