Question

5. Resolva as equações do 2º grau em. R.
a) x2 - 8x + 15 = 0​

Answer 1

Explicação passo-a-passo:

$x^2-8x+15=0$

$\Delta=(-8)^2-4\cdot1\cdot15$

$\Delta=64-60$

$\Delta=4$

$x=\dfrac{-(-8)\pm\sqrt{4}}{2\cdot1}=\dfrac{8\pm2}{2}$

$x'=\dfrac{8+2}{2}~\longrightarrow~x'=\dfrac{10}{2}~\longrightarrow~x'=5$

$x"=\dfrac{8-2}{2}~\longrightarrow~x"=\dfrac{6}{2}~\longrightarrow~x"=3$

$S=\{3,5\}$