Question

Quais são as equações do 2º grau?
a) x² + 4x - 5 = 0
b) 6x² - x=0
c) x+x= 10
d) 3x² = 0
e) - X2 - 4= 0
f) - X - 3x +9 = 0

preciso pra entregar agoraaa pfvr ajudem ​

Answer 1

Resposta:

alternativas a b e d

Explicação passo-a-passo:

espero que tenha ajudado

Answer 2

a) x² + 4x - 5 = 0

$x^2+4x-5=0$

$x_{1,\:2}=\frac{-4\pm \:6}{2\cdot \:1}$

$x_1=\frac{-4+6}{2\cdot \:1},\:x_2=\frac{-4-6}{2\cdot \:1}$

$\frac{-4+6}{2\cdot \:1}\\\\=\frac{2}{2\cdot \:1}\\\\=\frac{2}{2}\\\\=1$

$\frac{-4-6}{2\cdot \:1}$

$=\frac{-10}{2\cdot \:1}$

$=-\frac{10}{2}$

$=-5$

$x=1,\:x=-5$

b) 6x² - x=0

$x_{1,\:2}=\frac{-\left(-1\right)\pm \sqrt{\left(-1\right)^2-4\cdot \:6\cdot \:0}}{2\cdot \:6}$

$x_{1,\:2}=\frac{-\left(-1\right)\pm \:1}{2\cdot \:6}$

$x_1=\frac{-\left(-1\right)+1}{2\cdot \:6},\:x_2=\frac{-\left(-1\right)-1}{2\cdot \:6}$

$\frac{-\left(-1\right)+1}{2\cdot \:6}$

$=\frac{1+1}{2\cdot \:6}$

$=\frac{2}{2\cdot \:6}$

$=\frac{2}{12}$

$=\frac{1}{6}$

$\frac{-\left(-1\right)-1}{2\cdot \:6}$

$=\frac{1-1}{2\cdot \:6}$

$=\frac{0}{2\cdot \:6}\\\\=\frac{0}{12}\\\\=0$

$x=\frac{1}{6},\:x=0$

c) x+x= 10

$x+x=10\\\\2x=10\\\\\frac{2x}{2}=\frac{10}{2}\\\\x=5$

d) 3x² = 0

$3x^2=0$

$\frac{3x^2}{3}=\frac{0}{3}$

$x^2=0$

$x=0$

e) - X2 - 4= 0

$-x\cdot \:2-4=0$

$-x\cdot \:2-4+4=0+4$

$-x\cdot \:2=4$

$\frac{-x\cdot \:2}{-2}=\frac{4}{-2}$

$x=-2$

f) - X - 3x +9 = 0

$-x-3x+9=0$

$-4x+9=0$

$-4x+9-9=0-9\\\\-4x=-9\\\\\frac{-4x}{-4}=\frac{-9}{-4}\\\\x=\frac{9}{4}$

Letra A e Letra B