Question

resolva as equações do 2º grau ,sendo u=ir : 1º caso -5ײ+3×-4=0​

Answer 1

Resposta:

$-5x^2+3*-4=0\\\\-5x^2-12=0\\\\-5x^2-12+12=0+12\\\\-5x^2=12\\\\\frac{-5x^2}{-5}=\frac{12}{-5}\\\\x^2=-\frac{12}{5}\\\\x=\sqrt{-\frac{12}{5}}\\\\\:x=-\sqrt{-\frac{12}{5}}\\\\x=i\frac{2\sqrt{15}}{5}\\\\\:x=-i\frac{2\sqrt{15}}{5}$