xy=-504
x+y=7
subtract y from both sides
x=7-y
subsitute 7-y for x
(7-y)(y)=-504
7y-y^2=-504
add (y^2-7y) to both sides
0=y^2-7y-504
use quadratic formula which is
x=[tex] \frac{-b+/- \sqrt{ b^{2}-4ac } }{2a} [/tex] subsitute
ax^2+bx+c
a=1
b=-7
c=-504
x=[tex] \frac{-(-7)+/- \sqrt{ -7^{2}-4(1)(-504) } }{2(1)} [/tex]
x=[tex] \frac{7+/- \sqrt{ 49-(-2016) } }{2} [/tex]
x=[tex] \frac{7+/- \sqrt{ 49+2016 } }{2} [/tex]
x=[tex] \frac{7+/- \sqrt{ 2065 } }{2} [/tex]
x=[tex] \frac{7+/- \sqrt{ 2065 } }{2} [/tex]
x=[tex] \frac{7+\sqrt{ 2065 } }{2} [/tex] or x=[tex] \frac{7- \sqrt{ 2065 } }{2} [/tex]
