Question

answer is 152 from answer sheet. please give me full solution​

Answer 1

Let the two numbers be x and y.

x+y = 8

xy = 15

To find : x³+y³

(x+y)³ = x³+y³+3xy(x+y)

=> (x+y)³ - 3xy(x+y) = x³+y³

=> (8)³ - 3(15)(8) = x³+y³

=> 512 - 360 = x³ + y³

=> x³ + y³ = 152.

Hope it helps u...

Answer 2

Let the numbers be a and b.

given, their sum (a+b) = 8

      their product (ab) = 15

The formula is (a+b)³ = a³+b³+3ab(a+b)

from this, a³+b³ = (a+b)³ - 3ab(a+b)

Now, a³ +b³ = 8³ - 3*15*8

                    = 512 - 360

                    = 152