Question

Calcule as raízes da função f(x) = x² + 2x - 3. * 3 pontos a) 1 e -3 b) 6 e - 2 c) 18 e 0 d) 1 e 0 e) 2 e -3

Answer 1

Resposta:

Alternativa a)

Explicação passo-a-passo:

$\displaystyle Aplicando~a~f\'{o}rmula~de~Bhaskara~para~x^{2}+2x-3=0~~\\e~comparando~com~(a)x^{2}+(b)x+(c)=0,~temos~a=1{;}~b=2~e~c=-3\\\\\Delta=(b)^{2}-4(a)(c)=(2)^{2}-4(1)(-3)=4-(-12)=16\\\\x^{'}=\frac{-(b)-\sqrt{\Delta}}{2(a)}=\frac{-(2)-\sqrt{16}}{2(1)}=\frac{-2-4}{2}=\frac{-6}{2}=-3\\\\x^{''}=\frac{-(b)+\sqrt{\Delta}}{2(a)}=\frac{-(2)+\sqrt{16}}{2(1)}=\frac{-2+4}{2}=\frac{2}{2}=1\\\\S=\{-3,~1\}$