Question

dadas as equações 3x²-9=0 e x²-25=0. a soma das raízes dessas equações é:
a) 3
b)5
c)7
d)9​

Answer 1

Equação de 2° grau:

• Temos que resolver as duas equações e depois somar todas as raízes:

$\sf \bullet ~ 1^{\circ}\to \\\\\\3x^2-9=0\\\\\\3x^2-9+9=0+9\\\\\\\sf 3x^2=9\\\\\\x^2=\dfrac{9}{3}\to \boxed{\sf S_{1,2}=3,3}$

$\sf \bullet~ 2^{\circ}\to \\\\\\x^2-25=0\\\\\\\sf x^2-25+25=0+25\\\\\\\sf x^2=25\to \sqrt{25}\to \boxed{\sf S_{1,2}=5,5}$

Somando as raízes:

$\sf 3+5=\boxed{\sf 7}$