x, y - the numbers
The numbers add to 9 and multiply to -70.
[tex]x+y=9 \\
xy=-70 \\ \\
y=9-x \\
xy=-70 \\ \\
\hbox{substitute 9-x for y in the second equation:} \\
x(9-x)=-70 \\
9x-x^2=-70 \\
-x^2+9x+70=0 \\
-x^2+14x-5x+70=0 \\
-x(x-14)-5(x-14)=0 \\
(-x-5)(x-14)=0 \\
-x-5=0 \ \lor \ x-14=0 \\
x=-5 \ \lor \ x=14 \\ \\
y=9-x \\
y=9-(-5) \ \lor \ y=9-14 \\
y=14 \ \lor \ y=-5 \\ \\
(x,y)=(-5,14) \hbox{ or } (x,y)=(14,-5)[/tex]
The numbers are -5 and 14.
