Question

6) Determine as raizes reais das equaçoes incompletas: A) x2-5x =0 B) -x2+ 12=0 C) 5x2+ x=0 D) x2- 9x=0 E)X2-9=0 F) 25x2 -1=0 G) x2-64=0 H) x2+16=0 I) -7x2+28=0 J) (x-7) (x-3) +10=30 K) 2x(x=1)=X(x+5 ) +3 (12-x)              
 ME AJUDEM PFV

Answer 1

a
x² - 5x = 0
x( x- 5 ) = 0
x = 0****
x - 5 = 0 
x =5 ****

b
-x² + 12 = 0
x² - 12 = 0
x² = 12
Vx² = +-V12= +-V2² * V3 = +-2V3 ***

c
5x² + x = 0
x( 5x + 1) = 0
x = 0 ***
5x + 1 = 0
5x = -1
x =-1/5 ***

d
x² -9x = 0
x( x - 9 ) = 0
x = 0 ***
x - 9 = 0
x = 9 ****

e
x² - 9 = 0
( x + 3 ) ( x - 3) = 0
x + 3 = 0
x = -3 ***
( x - 3) = 0
x = 3 ****

f
25x² - 1 = 0  >binômio quadrado perfeito 

( 5x + 1) (5x - 1) = 0
5x + 1 = 0
5x = -1
x = - 1/5 ***
5x - 1 = 0
5x   = 1
x = 1/5 ***

g
( x² - 64 ) = 0
( x + 8) ( x - 8) = 8
x + 8 = 0
x = -8 ***
x - 8 = 0
x = 8 ***

h
x² + 16 = 0
x² = -16
Vx² = +-V-16  não ha  raizes no  campo real

i
-7x² + 28 = 0 ( dvidindo por 7 e trocando o sinal )
x² - 4 = 0 ( quadrado perfeito -0 binômio )
( x + 2) ( x - 2) = 0
x + 2 = 0
x = -2 ***
x - 2 = 0
x = 2 ***

j
( x - 7 )( x - 3) + 10 = 30
x² - 3x -7x + 21 + 10 = 30
x² - 10x + 31 - 30 = 0
x² - 10x = 0
x( x - 10 ) = 0
x = 0 ***
x - 10 = 0
x = 10 ***

K -0 ERRADA REFAÇA