Question

If x-y=7 an xy=9,find the value of (x square + y square.

Answer 1

Answer:67

Step-by-step explanation:

Please find the attached file.

Answer 2

Answer:

x²+y² = (x-y)² + 2xy = 7² + 18 = 67

Step-by-step explanation:

Take x - y = 7 and square both sides  

(x - y)^2 = 7^2  

x^2 - 2xy + y^2 = 49  

Move the -2xy term to the opposite side by adding 2xy to both sides  

x^2 + y^2 = 49 + 2xy  

Since xy = 9, 2xy = 18  

x^2 + y^2 = 49 + 18  

x^2 + y^2 = 67