Răspuns :
[tex]a) \: x {}^{2} - 4 = 0 \\ x {}^{2} = 4 \\ x = + - 2 \\ \\ b) \: 9x {}^{2} - 1 = 0 \\ 9x {}^{2} = 1 \\ {x}^{2} = \frac{1}{9} \\ x = \frac{1}{3} [/tex]
[tex]a) \: x {}^{2} - 4 = 0 \\ x {}^{2} = 4 \\ x = + - 2 \\ \\ b) \: 9x {}^{2} - 1 = 0 \\ 9x {}^{2} = 1 \\ {x}^{2} = \frac{1}{9} \\ x = \frac{1}{3} [/tex]