Question

A) x²-3x-28=0
B) x²-x-12=0

Answer 1

a) x^2-3x-28=0
delta=b^2-4ac
delta=(-3)^2-4.1.(-28)
delta=9+112
delta=121
x=-b-/+ raiz de delta/2a
x=-(-3)-11/2.1
x=3-11/2
x=-8/2
x=-4
x=-(-3)+11/2.1
x=3+11/2
x=14/2
x=7
b) x^2-x-12=0
delta=b^2-4ac
delta=(-1)^2-4.1.(-12)
delta=1+48
delta=49
x=-b-/+ raiz de delta/2a
x=-(-1)-7/2.1
x=1-7/2
x=-6/2
x=-3
x='-(-1)+7/2.1
x=1+7/2
x=8/2
x=4

Answer 2

x² - 3x - 28 = 0
a = 1; b = - 3; c = - 28

Δ = b² - 4ac
Δ = (-3)² - 4.1.( - 28)
Δ = 9 + 112
Δ = 121

x = - b +/- √Δ  = - ( - 3) +/- √121
          2a                  2.1

x = 3 + 11  = 14/2 = 7
         2

x = 3 - 11  = - 8/ 2 = - 4
        2

R.: x = 7 e  x = - 4
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b)
x² - x - 12 = 0
a = 1; b = - 1; c = - 12

Δ = b² - 4ac
Δ = ( - 1)² - 4.( 1). ( - 12)
Δ = 1 - 4. ( - 12)
Δ = 1 + 48
Δ = 49

x = - b +/- √Δ = - ( - 1) +/- √49
           2a                 2.1

x = 1 + 7 = 8/2 = 4
         2

x = 1 - 7 = - 6/2 = - 3
        2

R.: x = 4 e x = - 3