Question

me ajudem por favor ????

Answer 1

1
x² - 2x - 15 = 0
delta = 4 + 60 = 64 =  +-V64 = +-8 ****

x = ( 2 +-8)/2
x1 = 10/2 = 5 ***
x2 = -6/2 = -3 ******  ( c )

2
2x² - 4x + 10 = 0
a = 2
b = - 4
c = +10
x1 + x2 =  -b/a = 4/2 = 2 ***
x1*x2 =  c/a =  10/2 = 5 ****  ( b )

3
S = -b/a = 3
P = c/a = 4
x² - Sx + P = 0
x² - 3x + 4 = 0 ( a )

4
a
x² - 9 = 0
( x + 3) ( x - 3) = 0
x + 3 = 0
x = - 3 ***
x - 3 = 0 
x = 3 ***
b
25x² - 1 = 0
( 5x + 1) ( 5x - 1) = 0
5x + 1 = 0
5x = -1
x = - 1/5 ***
5x - 1 = 0
5x = 1
x = 1/5 ****
c
x² - 64 = 0
( x + 8)(x - 8) = 0
x + 8 = 0
x = -8 ****
x - 8 = 0
x = 8 ****
d
( x² + 16 ) = 0
x² = -16
x = V-16
não há raizes no campo real

5a
x² - 16x + 64 = 0
( x - 8)² = 0
x - 8 = 0
x = 8 ****
b
6x² -x - 5 = 0
delta = 1 +120 = 121 ou +-V121 = +-11 ****
x = ( 1 +-11)/12
x1 = 12/12 = 1 ****
x2 = -10/12 = -5/6 ***

c
x² - 6x - 16 = 0
delta = 36 + 64 = 100 ou +-V100 = +-10 ****

x = ( 6 +-10)/2
x1 =16/2 = 8 ****
x2 = -4/2 = -2 ****