Question

If x-y=9 and xy=2,find the value of (x square + y square)

Answer 1

Answer:

x² + y² = 85

Step-by-step explanation:

Using the expansion

(x - y)² = x² + y² - 2xy , then

x² + y² - 2xy = (x - y)² ( add 2xy to both sides )

x² + y² = (x - y)² + 2xy ← substitute given values

          = 9² + 2(2)

          = 81 + 4

          = 85