9th grade math
posted by anonymous on .
Which of the linear systems has exactly one solution
A: x+y=9
xy=9
B: x+y=9
xy= 9
C: x+y=9
xy=9
D: xy= 9
x+y= 9

Start putting all the equations into the same form y = a*x + b
A: x+y=9; y =x + 9
xy=9; x = 9 + y; y =x9
These two are not the same
B: x+y=9; y = 9+x
xy= 9; x = 9+y; y = x+9
These two are the same
C: x+y=9; y = 9+x
xy=9; y = 9+x; y = x 9
These two are not the same
D: xy= 9; x+9 = y
x+y= 9 ; y = x9
These two are not the same
The correct answer is B