Question

Find the value of x^3+ y^3

+ 15xy – 125 if x + y = 5.

Answer 1

x+y=5 
cubing both side, 
(x+y)^3=x^3+y^3+3xy(x+y); 
Putting the value of x+y; 
125=x^3+y^3+3xy(5) 
125=x^3+y^3+15xy 

Thus, 
x^3+y^3+15xy-125=0

Answer 2

Plzzz SUBSCRIBE my YouTube channel (BanarasiiiINDIA) if this answer is helpful for you.

This is my YouTube channel Link-

https://www.youtube.com/channel/UC27NLinpXVunbzVQ0vdHabQ

x+y=5

cubing on both sides

(x+y)^3=125

x^3+y^3+3xy(x+y)=125

x^3+y^3+3xy(5)=125. (Since x+y=5)

x^3+y^3+15xy=125

Thus

x^3+y^3+15xy-125=0

Don't forget to SUBSCRIBE my YouTube channel (BanarasiiiINDIA) if this answer is helpful for you.

This is my YouTube channel Link-

https://www.youtube.com/channel/UC27NLinpXVunbzVQ0vdHabQ

Thank You!