Question

If x+y=10 and xy=25 find the value of x^3+y^3

Answer 1

Hey....!! HERE IS YOUR SOLUTION.....!!

◾ACCORDING TO 1st CONDITION...

x + y = 10
x = 10 - y..........[1]......

◾ACCORDING TO 2nd CONDITION...

xy = 25
x = 25/y...........[2]......

◾FROM EQN...1 AND 2..,

10 - y = 25/y
10y - y^2 = 25
-y^2 + 10y - 25 = 0
-y^2 +(5 + 5)y - 25 = 0
-y^2 + 5y + 5y - 25 = 0
-y [ y - 5 ] + 5 [ y - 5 ] = 0
[ - y + 5 ] [ y - 5 ] = 0

If - y + 5 = 0
- y = -5
y = 5.....

If y - 5 = 0
y = 5........

SUBSTITUTE THE VALUE OF Y IN EQN.....2 ,

x = 25 / y
x = 25 / 5
x = 5.......

{ x = 5 ; y = 5 }

⏮ ▶ ⏭.........

TO FIND THE VALUE OF x^3 + y^3 ,

x^3 + y^3
= 5^3 + 5^3
= 125 + 125
= 250....

THE ANSWER IS 250........

HOPE IT'S WILL HELP YOU A LOT.....!!
@ujjwalusri