Question

resouva essa equação do 2º grau:    -x² - x + 30= 0

Answer 1

$-x^2-x+30=0$

$\Delta=(-1)^2-4\cdot(-1)\cdot30=1+120=121$

$x=\dfrac{-(-1)\pm\sqrt{121}}{2\cdot(-1)}=\dfrac{1\pm11}{-2}$

$\rhd$ $x'=\dfrac{1+11}{-2}=\dfrac{12}{-2}=-6$

$\rhd$ $x"=\dfrac{1-11}{-2}=\dfrac{-10}{-2}=5$

$S=\{-6, 5\}$