Question

if a+b=10,ab=3 find a³+b³​

Answer 1

EXPLANATION.

=> a + b = 10

=> ab = 3

To find the value of a³ + b³.

=> a + b = 10 .......(1)

=> ab = 3 ........(2)

From equation (2) we get,

=> ab = 3

=> a = b/3 .......(3)

put the value of equation (3) in equation (1)

we get,

=> b/3 + b = 10

=> b + 3b = 30

=> 4b = 30

=> b = 30/4

=> b = 15/2

Put the value of b = 15/2 in equation (3)

we get,

=> a = b/3

=> a = 15/2/3

=> a = 15/2 X 1/3

=> a = 5/2

Formula of => a³ + b³

=> ( a + b ) ( a² - ab + b² )

=> ( 5/2 + 15/2 ) [ ( 5/2)² - ( 5/2 X 15/2 ) + ( 15/2)²

=> 10 [ 25/4 - 75/4 + 225/4 ]

=> 10 [ 250 - 75 / 4 ]

=> 10 [ 175/4 ]

=> 5 X 175 / 2

=> 875/2

Therefore,

value of a³ + b³ = 875/2.

Answer 2

Step-by-step explanation:

( a + b ) ³ = 10³

a³+b³+3ab(a+b)= 1000

a³+b³+3*3(10)= 1000

a³+b³+9*10= 1000

a³+b³+90= 1000

a³+b³= 1000 - 90

a³+b³= 910