Question

ao aplicar a fórmula de Bhaskara para resolver a equação X(elevado a 2) - 3x - 28 = 0 ,encontramos as raízes:
A) {-4,7}
B) {-4,- 7}
C) {4,7}
D) {4,2}
E) {7,2}​

Answer 1

Resposta:

Alternativa a)

Explicação passo-a-passo:

x²-3x-28=0

$\displaystyle Aplicando~a~f\'{o}rmula~de~Bhaskara~para~x^{2}-3x-28=0~~\\e~comparando~com~(a)x^{2}+(b)x+(c)=0,~temos~a=1{;}~b=-3~e~c=-28\\\\\Delta=(b)^{2}-4(a)(c)=(-3)^{2}-4(1)(-28)=9-(-112)=121\\\\x^{'}=\frac{-(b)-\sqrt{\Delta}}{2(a)}=\frac{-(-3)-\sqrt{121}}{2(1)}=\frac{3-11}{2}=\frac{-8}{2}=-4\\\\x^{''}=\frac{-(b)+\sqrt{\Delta}}{2(a)}=\frac{-(-3)+\sqrt{121}}{2(1)}=\frac{3+11}{2}=\frac{14}{2}=7\\\\S=\{-4,~7\}$