Question

x²-3x - 10 = 0
.......

Answer 1

Resposta:

S={-2,5}

Explicação passo-a-passo:

Resolução :

x² - 3x - 10=0

Δ=b² - 4.a.c

Δ= (-3)² - 4.1.(-10)

Δ= 9 +40

Δ= 49

x= - b±√Δ

______

2.a

X= - (-3)±√49

________

2. 1

x= 3 ± 7

______

2

X' = 3 - 7 - 4

_____=___ = - 2

2 2

X" = 3 +7 10

_____= ___= 5

2 2

S={-2,5}

Answer 2

$x^2-3x-10=0$

$a=1\quad b=-3\quad c=-10$

$\Delta=b^2-4\cdot a\cdot c$

$\Delta=(-3)^2-4\cdot1\cdot(-10)$

$\Delta=9+40$

$\Delta=49$

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

$x=\dfrac{-(-3)\pm\sqrt{49}}{2\cdot 1}$

$x=\dfrac{3\pm7}{2}\begin{cases}x'=\dfrac{3+7}{2}=\dfrac{10}{2}=5\\\\x''=\dfrac{3-7}{2}=-\dfrac{4}{2}=-2\end{cases}$

$\boxed{\boxed{S=\{-2\,;\,5\}}}$