[tex] a^{2}+9b^{2}+4a-6b+5 = 0 \Rightarrow \\ (a^{2} + 2 \cdot 2 \cdot a + 2^{2} ) + (3b)^{2} - 2 \cdot 1 \cdot 3b + 1^{2} = 0 \Rightarrow \\ (a+2)^{2} + (3b-1)^{2} = 0 \Rightarrow \\ (a+2)^{2} = 0 \rightarrow a = -2 \\ (3b-1)^{2} = 0 \rightarrow b= \dfrac{-1}{3} [/tex]
