[tex] \sqrt{x + 1} = 5 - x | {}^{2} \\ \sqrt{(x + 1) {}^{2} } = (5 - x) {}^{2} \\ x + 1 = 5 {}^{2} - 2 \times 5 \times x + x {}^{2} \\ x + 1 = 25 - 10x + x {}^{2} \\ 0 = 25 - 10x + x {}^{2} - x - 1 \\ x {}^{2} - 11x + 24 = 0[/tex]
{a=1
{b=-11
{c=24
∆=b²-4ac = (-11)²-4•1•24=121-96=25=5²
[tex]x1 = \frac{ - b + \sqrt{∆} }{2a} = \frac{11 + 5}{2} = \\ \\ x1 = \frac{16}{2} = 8 \\ \\ \\ x2 = \frac{ - b - \sqrt{∆} }{2a} = \frac{ 11 - 5}{2} \\ \\ x2 = \frac{6}{2} = 3[/tex]
S = { 3 ; 8 }
______Explicatie_______
(a-b)²=a²-2ab+b²
formula asta am folosit-o pentru a calcula
(5-x)²
