Question

gostaria da resposta dessas 4 questões obg

Answer 1

a - apagada
b
7x² - 21 = 0
x² - 3 = 0
x² = 3
x = +-V3 *****
c
x² + 9 = 0
x² = -9
c = +-V-9   impossivel ***
d
x² - 49 = 0
x² = 49
x = +-7 ***
e
5x² - 20 = 0
x² - 4 = 0
x² = 4
x = +-V4 = +-2 ***
=====================================================
x² + 8x + 15 = 0
delta = 64 - 60 = 4 ou +-V4 = +-2 ****
x = ( -8 +-2)/2
x1 = -10/2 = -5 ***
x2 = -6/2 = -3 ****

b
x² - 9x + 14 = 0
delta = 81 - 56 =25 ou +_V25 = +-5 *****
x = ( 9 +-5)/2
x1 = 14/2 = 7 ****
x2 = 4/2 = 2 ****
c
x² + 6x + 8 = 0
delta = 36 - 32 = 4 ou +_V4 = +- 2 ****
x = ( -6 +-2)/2
x1 = -4/2 = -2 ****
x2 = -8/2 = -4 ****

===================================================
9x² - 25 = 0
a = 9
b = 0
c = -25
S = -b/a = 0/9 = 0
P = c/a = -25/9 ****
b
3x² - 2x + 8 = 0
a = 3
b = -2
c = +8
S = -b/a = 2/3 ***
P = c/a = 8/3 ***
c
4x² - 5x = 0
a = 4
b = -5
c = 0
S = -b/a = 5/4 ****
P = c/a = 0/4 = 0 ****
d
-6x² - x + 1 = 0
a = -6
b = -1
c = +1
S = -b/a =  1/-6  = - 1/6 ***
P = c/a =  1/-6   = - 1/6 ***