Solution: Group and complete the square: $ 4(x^2 + 2x) - 9(y^2 - 2y) = 11 $. Complete squares: $ 4[(x+1)^2 - 1] - 9[(y-1)^2 - 1] = 11 $. Expand: $ 4(x+1)^2 - 4 - 9(y-1)^2 + 9 = 11 \Rightarrow 4(x+1)^2 - 9(y-1)^2 = 6 $. Rewrite: $ \frac(x+1)^2\frac32 - \frac(y-1)^2\frac23 = 1 $. Center at $ (-1, 1) $. \boxed(-1, 1)1. **A chemistry experiment requires 50 mL of a 10% salt solution. If you only have a 20% salt solution and distilled water, how much of each should be mixed to obtain the desired concentration? - go-checkin.com