Question

Resolva as seguintes equações, sendo U = R.

a) $x^{2} -25=0$

b) $2x^{2} -18=0$

c) $7x^{2} -14=0$

d) $x^{2} +25=0$

e) $2^{2} -49=0$

f) $2x^{2} -50=0$

g) $7x^{2} -7=0$

h) $4x^{2} =36$

i) $5x^{2} -15=0$

Answer 1

A-

$x^{2}=25 \\ x = \sqrt{25} = 5$

B-

$2x^{2} =18\\ x = \sqrt{\frac{18}{2}} = \sqrt{9}= 3$

C-

$7x^{2} =14\\ x = \sqrt{\frac{14}{7}}=\sqrt{2}$

D-

$x^{2}=-25\\ x = \sqrt{-25}= \sqrt{25\times \sqrt{-1} }= 5i$

E-

$2^{2} - 49 = 8 -49 = -41$

F-

$2x^{2} =50\\ x= \sqrt{25} = 5$

G-

$7x^{2}=7\\x^{2}= 1 \\ x= 1$

H-

$4x^{2} =36\\x = \sqrt{\frac{36}{4}}= \sqrt{9} =3$

I-

$5x^{2}=15\\ x = \sqrt{\frac{15}{5}}= \sqrt{3}$