1.x²+4x-96> 0
2.x²+3x-28< =0
3.x²-16x+64> =0

1.x1=8; x2=-12

2.найди D

D=9+4*28=121= 11 кв

х1=(-3+11)\2= 4

х2=(-3-11)\2= -7

2. приравниваем к нулю :

x^2+ 16x + 64 = 0  

a = 1 ; b=16 ; c=64

b^2 - 4ac = 16^2 - 4*1*64 = 256 - 256 = 0.

x1 = -16+0/2*1 = -8

x2 = -16-0/2*1 = -8