Question

Me ajudem 
4x²-12x-7=0 ? 

Answer 1

a= 4   b= -12  c= -7
delta = 144-4.4.-7
delta= 144+112 = 256
x=12+/-√256
     8 
x1=12+16/8 = 28/8 = 7/2
x2= 12-16/8 = -4/8 = -1/2

Answer 2

4x²-12x-7=0
Δ= 12²-4.4.(-7)
Δ=144+112
Δ=256 

Resolvendo bhaskara
-b+ou-√256/2.a
X1= 12+16/8= 28/8 (simplificando por  2 dica 14/4)
X2= 12-16/8= -4/8 (simplificando fica -1/2)