Question

http://i1142.photobucket.com/albums/n608/nancylam67/page267.jpg

Answer 1

9=3^2, 5 can be 0+5, 1+4, or 2+3, therefore no two numbers can give a sum of 5 and a product of 9.

Answer 2

x+y = 5
x*y = 9

x = y - 5 substitute it to x*y =9
then, you get y*y - 5*y - 9 = 0
then, y =( 5 +- sqrt(61) ) / 2

Answer 3

weiwei, wouldn't x=5-y? so it is (5-y)y=9, which then is 5y-y^2-9=0