Question

Resolve as equações completas do 2 grau através da formula de bhaskara,sendo U=R   -x^2-9x+8=0  S={1;8}

Answer 1

Resolvendo a equação, temos:

$x^{2}-9x+8=0$

$\Delta=b^{2}-4\cdot a\cdot c$
$\Delta=(-9)^{2}-4\cdot1\cdot8$
$\Delta=81-32$
$\Delta=49$

$x=\dfrac{-b\pm\sqrt{\Delta}}{2a}$

$x=\dfrac{9\pm\sqrt{49}}{2\cdot1}$

$x=\dfrac{9\pm7}{2}$

$\Longrightarrow\;x_{1}=\dfrac{9+7}{2}=\dfrac{16}{2}=8$

$\Longrightarrow\;x_{2}=\dfrac{9-7}{2}=\dfrac{2}{2}=1$

$S=\{1,\;8\}$

Answer 2

-x^2-9x+8=0
a=1
b=-9
c=8

x= -b + sqrt{delta}/2*a

x= -b - sqrt{delta}/2*a

delta = b²-4*a*c
delta = (-9)²-4*1*8
delta = 81-32
delta = 49


x= -(-9) + sqrt{49}/2*1
x= 9 + 7/2
x= 16/2
x=8


x= -(-9) - sqrt{49}/2*1
x= 9 - 7/2
x= 2/2
x=1

sqrt{delta} significa raíz de delta