Question 135322
The number [x,y] .. example: x = 2 and y = 3 .. so [2,3] or 23
[x,y] is the number represented by 10x + y
10x + y = x^2 + y^2 + 19
10x + y = 2xy + 44
Now, take the second:
10x + y = 2xy + 44
y - 2xy = 44 - 10x
y(1 - 2x) = 44 - 10x
y = (44 - 10x)/(1 - 2x)
Now, plug:
10x + y = x^2 + y^2 + 19
10x + (44 - 10x)/(1 - 2x) = x^2 + [(44 - 10x)/(1 - 2x)]^2 + 19
Long story short: (7,2) and (3.5,-1.5) .. the decimals are excluded because they don't result with two digits
10x + y
10(7) + 2
72