2、9x^2- 16=9(x^2+x-6)

9x^2- 16=9x^2+9x-54

9x=54- 16

9x=38

x=38/9

3. The original formula = x2-4Y2-(y2-4x2) = x2-4Y2-y2+4x2 = 5x2-5Y2 = 5 (x2-y2) = 5 (x+).