Question 22588
Multiply thru by 16 to get x^2+y^2 = 16
Substitute y=x+3  to get:
       x^2 +x^2+6x+9=16
       2x^2 + 6x -7 =0
Use the quadratic formula to get 
*[invoke quadratic "x", 2,6,-7]

Cheers,
Stan H.