Question

equação do 2 grau incompleta responda : a)  x² =16  b) x² =3x  c) 3x² + 2x = 0    d) x+ 5x² =2x  e) x² -64 = 0 f) 6x² + 18x =0   g) x² -8x = 0     h) 2x²+ 5x =0  i) 7x² -21 =0                       ME AJUDEM PFV E PRA AMANHAM

Answer 1

a)  x² =16
   
x = ± √16
   
x = ±  4

S[- 4 ,+ 4]


 
b) x² =3x  

x² - 3x = 0

x.(x - 3) = 0

x = 0

(x- 3) =  0

x - 3 = 0

x =  3

S[0 , 3]




c) 3x² + 2x = 0

x(3x + 2) = 0

x =  0

(3x + 2) = 0

3x + 2 = 0

3x = - 2

x = - 2/3

S[- 2/3 ,  0]




d) x+ 5x² =2x  

5x² + x - 2x = 0

5x² - x = 0

x.(5x - 1) = 0

x = 0

(5x - 1) = 0

5x - 1 = 0

5x = + 1

x = 1/5


S[0 , 1/5]




e) x² -64 = 0

x² = 64

x = ± √64

x = ± 8


S[- 8 , + 8]




f) 6x² + 18x =0   ÷ (6)

x² + 3x = 0

x.(x + 3) = 0

x =  0

(x + 3) = 0

x + 3 = 0 

x = - 3


[- 3, 0]




g) x² -8x = 0    

x.(x - 8) = 0

x = 0

(x- 8 ) = 0

x - 8 = 0

x = + 8


S[0 , 8]



 
h) 2x²+ 5x =0

x(2x + 5) = 0

x = 0

(2x + 5) = 0

2x + 5 =0

x = 5/2 

x = 2,5

S[0, 2,5]



 i) 7x² -21 =0    ÷ (7)   

x² - 3 = 0

x² = + 3

x =  ± √3

S[- √3 , + √3]