Question

Quais são as raízes da equação x²-14x+48=0?

a) S={9 e 10}
b) S={4 e 8}
c) S={6 e 8}
d) S={1 e 5}
e) S={-6 e -4}

Answer 1

$\triangle=b^2-4.a.c=(-14)^2-4.1.48=196-192=4$

$x_1=\frac{-b+\sqrt{\triangle} }{2a}=\frac{14+\sqrt{4} }{2\cdot 1}=\frac{14+2}{2}=\frac{16}{2}=8$

$x_2=\frac{-b-\sqrt{\triangle} }{2a}=\frac{14-\sqrt{4} }{2\cdot 1}=\frac{14-2}{2}=\frac{12}{2}=6$

$S=\{6\ e\ 8\}$