Question

Resolva com a fórmula de baskára: -x²-3x+4=0

Answer 1

Explicação passo-a-passo:

Resolvendo a equação de segundo grau:

$-x^{2} -3x+4=0\implies a=-1;\ b=-3;\ c=4\\\\\Delta=b^{2}-4ac \\\\\Delta=(-3)^{2}-4.(-1).4=9+16\\\\\Delta=25\\\\x=\dfrac{-b\pm \sqrt{\Delta} }{2a} \\\\x'=\dfrac{-(-3)+\sqrt{25} }{2.(-1)} =\dfrac{3+5}{-2}\\\\x'=\dfrac{8}{-2}\\\\\boxed{x'=-4} \\\\x''=\dfrac{-(-3)-\sqrt{25} }{2.(-1)} =\dfrac{3-5}{-2}\\\\x''=\dfrac{-2}{-2}\\\\\boxed{x''=1}$

$\boxed{\boxed{S=\{-4, 1\}}}$