Question

X al cuadrado- x- 20=0

Answer 1

$x {}^{2} - x - 20 = 0 \\ a = 1 \\ b = - 1 \\ c = - 20 \\ ( - 1) {}^{2} - 4 \times 1( - 20) \\ 81$

$x = \frac{1± \sqrt{81} }{2} \\ x = \frac{1±9}{2} \\ x = \frac{1 + 9}{2} \\ x = \frac{1 - 9}{2} \\ x_{1} = - 4 \\ x_{2} = 5$

S = {-4,5}