Question

Resolva as equaçõs do 2° grau.
a. 5x²-125=0

b. 6x²+18=0

c. 10x²+100x=0

d. 3x²+3x=0

e. 7x²+5x=0
f. 13x²+x=0

Answer 1

a)5.x²  -  125 = 0
5 x² = 125
x² = 125/5
x² = 25
x = + ou - √25
x = + ou - 5
S = {+5 ; -5 }

b)6 x² + 18 = 0
6 x² = -18
x² = -18/6
x² = - 3
x = + ou - √-3 não há raiz real

c)10 x²  +  100 x = 0
10 x(x + 10 ) = 0
10 x = 0
x = 0/10
x = 0
x + 10 = 0
x = - 10
S = {0 ; -10 }

d)3 x² + 3 x = 0
3 x(x + 1 ) = 0
3 x = 0
x = 0/3
x = 0

e)7 x² + 5 x = 0
x(7 x + 5 ) = 0
x = 0
7 x + 5 = 0
7 x = -5
x = -5/7
S = {0 ; -5/7 }

f)13 x² + x = 0
x(13 x + 1 ) = 0
x = 0
13 x + 1 = 0
13 x = -1
x = -1/13
S = {0 ; -1/13 }