Question

8. If x + y = 9 and xy = 20; find: a. x-y, b. -Y​

Answer 1

Answer:

very simple x+y= 9 and xy= 20

Formula is x-y = √(x+y)^2 -4xy

Answer 2

Answer:

x+y = 9

xy= 20

(x+y)² = 9²

x² + y² + 2xy = 81

x² + y² = 81 - 2*20

x² + y² = 81 - 40 = 41

x² + y² -2xy = 41 - 2xy

(x - y)² = 41 - 2*20 = 41 - 40 = 1

x-y = √1

x - y = 1