Question

determine as raizes das equações de 2 grau.
POR FAVORRR ME AJUDEMMM​

Answer 1

a)

${x}^{2} - 64 = 0 \\ {x}^{2} = 64 \\ x = + - \sqrt{64} \\ x = + - 8$

b)

${x}^{2} - 81 = 0 \\ {x}^{2} = 81 \\ x = + - \sqrt{81} \\ x = + - 9$

c)

${x}^{2} - 8x = 0 \\ x(x - 8) = 0 \\ x = 0 \\ \\ \\ x - 8 = 0 \\ x = 8$

d)

$2 {x}^{2} - 72 = 0 \\ 2 {x}^{2} = 72 \\ {x}^{2} = \frac{72}{2} \\ {x}^{2} = 36 \\ x = + - \sqrt{36} \\ x = + - 6$

e)

${x}^{2} - 9 = 0 \\ {x}^{2} = 9 \\ x = + - \sqrt{9} \\ x = + - 3$

f)

$4 {x}^{2} - 12x = 0 \\ x(4x - 12) = 0 \\ x = 0 \\ \\ \\ 4x - 12 = 0 \\ 4x = 12 \\ x = \frac{12}{4} \\ x = 3$

g)

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

h)

$7x(x - 3) = 0 \\ 7 {x}^{2} - 21x = 0 \\ x(7x - 21) = 0 \\ x = 0 \\ \\ \\ 7x - 21 = 0 \\ 7x = 21 \\ x = \frac{21}{7} \\ x = 3$