Question

-2x^2+26x-84=0 qual a raiz

Answer 1

Basta fazer Baskara:

$-2x^2+26x-84 \\ a = -2 \\ b=26 \\ c=-84 \\\\ b^2-4(a)(c) \\ 676-4(-2)(-84) \\ 676+672 \\ Delta=4 \\\\ \dfrac{-b+-\sqrt4}{2.a} = \dfrac{-26+-2}{4} \\\\\\ \dfrac{-26+2}{4}=\dfrac{-24}{4}=\dfrac{-12}{2}=-6 \\\\\\ \dfrac{-26-2}{4}=\dfrac{-28}{4}=\dfrac{-14}{2}=-7$

Raízes: {-7,-6}

Qualquer dúvida basta perguntar, bons estudos! :D