Question

B) X 2 - 3 X - 28 = 0

Answer 1

Δ = 9 + 112
Δ = 121

x = 3 +-√121/2
x = 3 +-11/2

x' = 14/2 = 7

x'' = -8/2 = -4               ok

Answer 2

x2-3x-28=0
Δ=b2-4ac
Δ=(-3)2-4.1.(-28)
Δ=9+112
Δ=121
x= -b+- √Δ÷2a
x=-(-3)+-√121÷2.1
x1=-3+11/2                x2=-3-11/2
x1=8/2                       x2=-14/2 
x1=4                          x2=-7
   solução:(4,-7)