Question

determine as raízes da equação do 2 grau:
a) x² - 9x+20=0
b)16- x² =0

Answer 1

$\mathtt{x^2 - 9x+20=0} \\ \\ \mathtt{a = 1 } \\ \mathtt{b = -9} \\ \mathtt{c = 20} \\ \\ \mathtt{\Delta = b^2-4\times a \times c } \\ \\ \mathtt{\Delta= (-9)^2 -4 \times 1 \times 20 } \\ \mathtt{\Delta = 81 -80} \\ \mathtt{\Delta = 1} \\ \\ \mathtt{\frac{-b+- \sqrt{\Delta}} {2\times a}} \\ \\ \mathtt{ \frac{- (-9) +- \sqrt{1} }{2 \times 1} } \\ \\ \mathtt{ \frac{9 +-1}{2} } \\ \\ \mathtt{x' = \frac{9 +1}{2} } \\ \\ \mathtt{x' =\frac{10}{2} } \\ \\ \mathtt{\underline{x' = 5} }$

$\mathtt{x" = \frac{9 - 1}{2}} \\ \\ \mathtt{x" = \frac{8}{2}} \\ \\ \mathtt{x" = \underline4} \\ \\ \boxed{\boxed{\mathtt{Resposta ~1 = S:4~,~5}}} \\ \\ \\ \mathtt{-x^2 + 16 = 0 } \\ \mathtt{-x^2 = -16} \\ \mathtt{x^2 = 16} \\ \mathtt{x =+- \sqrt{16}} \\ \mathtt{x = + - 4} \\ \\ \boxed{\boxed{\mathtt{Resposta~2 S = -4~,~4}}}$