Question

Encontre as raízes das equações do 2° grau incompletas:

a) x² - 49 = 0

b) 7x² + 2 = 30

c) 6x² + 18x = 0

d) - 16x² = 0

Answer 1

A)

${x}^{2} - 49 = 0$

A= 1

B= 0

C= -49

$delta = {0}^{2} - 4.1.( - 49)$

$delta = 0 + 49 = 49$

$x1 = \frac{ - 0 + 7}{2.1} = \frac{7}{2} = 3.5$

$x2 = \frac{ - 7}{2} = - 3.5$

B)

${7x}^{2} + 2 = 30$

${7x}^{2} + 2 - 30 = 0$

${7x}^{2} - 28 = 0$

A= 7

B= 0

C= -28

$delta = {0}^{2} - 4.7.( - 28)$

$delta = 0 + 784 = 784$

$x1 = \frac{ - 0 + 28}{2.7} = \frac{28}{14} = 2$

$x2 = \frac{ - 28}{14} = - 2$

C)

${6x}^{2} + 18x = 0$

A= 6

B= 18

C= 0

$delta = {18}^{2} - 4.6.0$

$delta = 324$

$x1 = \frac{ - 18 + 18}{2.6} = \frac{0}{12} = 0$

$x2 = \frac{ - 18 - 18}{12} = \frac{ - 36}{12} = - 3$

D)

${ - 16x}^{2} = 0$

A= -16

B= 0

C= 0

$delta = 0 {}^{2} - 4.( - 16).0$

$delta = 0 - 0 = 0$

$x1 = \frac{ - 0 + 0}{2.( - 6)} = \frac{0}{ - 12} = 0$

$x2 = \frac{ - 0 - 0}{ - 12} = 0$

Espero ter ajudado!