Răspuns:
[tex]( \sqrt{7 - x} ) {}^{2} = {1}^{2} \\ 7 - x = 1 \\ - x = 1 - 7 \\ - x = - 6 \\ x = 6[/tex]
[tex]( \sqrt{2 + x} ) {}^{2} = {x}^{2} \\ 2 + x = {x}^{2} \\ {x}^{2} - x - 2 = 0 \\ ecuatie \: de \: grad \: 2......a = 1.b = - 1.c = - 2 \\ delta ={b}^{2} - 4ac = 1 + 8= 9 \\ x1 = \frac{ - b - \sqrt{delta} }{2a} = \frac{ 1 - 3}{2} = - 1 \\ x2 = \frac{ - b + \sqrt{delta} }{2a} = \frac{1 + 3}{2} = 2[/tex]
