Question

8xy(x2+y2) if (x+y) =5&(x-y)=1

Answer 1

Answer:

8xy(x^2-y^2) = ? given that

x+y = √5 …(1) and

x-y = √3 …(2)

Multiply (1) and (2) to get (x^2-y^2) = √15

Add (1) and (2) to get 2x = (√5 + √3) …(3)

Subtract (2) from (1) to get 2y = (√5 - √3) …(4)

Therefore, 8xy(x^2-y^2) = 2*2x*2y*(x^2-y^2)

= 2*(√5 + √3)*(√5 - √3)*√15

= 2*2*√15

= 4√15. Answer

Answer 2

Answer:

x + y =5

x - y = 1

______

2x = 6

x = 3

x + y = 5

3 + y = 5

y = 2

 

8xy(x2 + y2)

8(3)(2)[9 + 4]

48 * 13

= 624