Question

resolva as seguintes equações incompletas: a) x² - 25 = 0 b) 2x² - 18 = 0 c) 2x² - 18 = 0 d) x² - 7x = 0 e) x² - 5x = 0 f) -2x² + 10x = 0

Answer 1

a)

${x}^{2} - 25 = 0 \\ {x}^{2} = 25 \\ x = + - \sqrt{25} \\ x1 = 5 \\ x2 = - 5$

b)

${2x}^{2} - 18 = 0( \div )2 \\ {x}^{2} - 9 = 0 \\ {x}^{2} = 9 \\ x = + - \sqrt{9} \\ x1 = 3 \\ x2 = - 3$

c)Está igual a letra b

d)

${x}^{2} - 7x = 0 \\ x(x - 7) = 0 \\ x1 = 0 \\ x - 7 = 0 \\ x2 = 7$

e)

${x}^{2} - 5x = 0 \\ x(x - 5) = 0 \\ x1 = 0 \\ x - 5 = 0 \\ x2 = 5$

f)

$- {2x}^{2} + 10x = 0( \div - 2) \\ {x}^{2} - 5x = 0 \\ x(x - 5) = 0 \\ x1 = 0 \\ x - 5 = 0 \\ x2 = 5$