The sum of two numbers is 19 and their difference is 1. What are the two numbers ?
Smaller number
Larger number

if x+y=19

and

x-y=1

now solve it by adding the equations together

x+x , y+[-y] and 19+1

2x=20

x=10, y=9

none of the above.

for one of the equations to be used in the process, there has to be a term in the equation since squared is .

since there is only a term in the first equation, we cannot derive a from completing the square.

solving with completing the square