[tex] {x}^{2} = 25[/tex]
[tex]x = \pm5[/tex]
[tex]S=\left\{-5,5\right\}[/tex]
[tex]9 {(x + 3)}^{2} = 16[/tex]
[tex]9( {x}^{2} + 6x + 9) = 16[/tex]
[tex]9 {x}^{2} + 54x + 81-16 = 0[/tex]
[tex]9 {x}^{2} + 54x + 65 = 0[/tex]
[tex]a = 9[/tex]
[tex]b = 54[/tex]
[tex]c = 65[/tex]
[tex]\Delta = {b}^{2} - 4ac[/tex]
[tex]\Delta = {54}^{2} - 4 \times 9 \times 65[/tex]
[tex]\Delta = 2916 - 2340 = 576[/tex]
[tex]x_{1,2}=\frac{-b\pm\sqrt{\Delta}}{2a} = \frac{ - 54 \pm \sqrt{576} }{2 \times 9} = \frac{ - 54 \pm24}{18} [/tex]
[tex]x_{1}= \frac{ - 54 + 24}{18} =- \frac{30}{18} = -\frac{5}{3} [/tex]
[tex]x_{2} = \frac{ - 54 - 24}{18} = - \frac{78}{18} = - \frac{13}{3} [/tex]
[tex]S=\left\{-\frac{13}{3},-\frac{5}{3}\right\}[/tex]
