Find the value of x 3 + y 3 + 15xy +125 when x + y =5
Answers
Answered by
1
(x+y)=5
cubing on both sides
⇒(x+y)³=5³
⇒x³+y³+3xy(x+y)=125
⇒x³+y³+3xy(5)=125
⇒x³+y³+15xy=125
∴x³+y³+15xy+125=125+125=250
cubing on both sides
⇒(x+y)³=5³
⇒x³+y³+3xy(x+y)=125
⇒x³+y³+3xy(5)=125
⇒x³+y³+15xy=125
∴x³+y³+15xy+125=125+125=250
Similar questions