Question

resolva as equações.
$x { }^{2} -x - 20 = 0$
$x {}^{2} - 3x + 4 = 0$
$x {}^{2} - 8x + 7 = 0$
$x {}^{2} - 3x - 5 = 0$

Answer 1

A)√B²-4ac
√(-1) -4(1).(-20)
√1+80
√81=9

x=+1+-9/2
X,=+1+9/2
X,=10/2
X,=5
X,,=+1-9/2
X,,=-8/2
X,,= -4


B)√b²-4ac=Δ
√(-3)²-4.(+1.+4)
√9-16
√-7 não possui raízes reais

C)Δ=√b²-4ac
√(-8)²-4.(+1.+7)
√64-28
√36=6
X=-8+-6/2
X,=-8+6/2
X,=-2/2
X,= -1



X,,=-8-6/2
X,,=-14/2
x,,= -7





d)Δ=√B²-4ac

√(-3)²-4(+1.(-5)
√9+20
√29
X=+3+-√29/2
X,+3+√29/2
x,,=+3-√29/2