Question

Determine as raízes das equações: a) x²-5x+6=0 b) x²-8x+12=0 c) x²+2x-8=0 d)x²-5x+8=0 e)2x²-8x+8=0 f)x²-4x-5=0 g)4+x(x-4)=x h)x(x+3)-40=0 ME AJUDEM PFVR

Answer 1

B)

Resposta:

Explicação passo-a-passo:

A) x² -5x +6= 0

Δ= (-5)² -4×1×6

Δ= 25 -24

Δ= 1

x= 5±1/2   x'= 6/2= 3    x"= 4/2= 2

B) x² -8x +12

Δ= (-8)² -4×1×12

Δ= 64 -48

Δ= 16

x= 8±4/2   x'= 12/2= 6   x"= 4/2= 2    

C) x² +2x -8= 0

Δ= 2² -4×1×(-8)

Δ= 4 + 32

Δ= 36

x= -2±6/2   x'= 4/2=2   x"= -8/2= -4

D) x² -5x +8= 0

Δ= (-5)² -4×1×8

Δ= 25 -32

Δ= -7

Δ=∅

E) 2x² -8x +8= 0

   x² -4x +4= 0

Δ= (-4)² -4×1×4

Δ= 16 -16

Δ=0

x= 4±0/2   x'= 4/2= 2

F) x² -4x -5= 0

Δ= (-4)² -4×1×(-5)

Δ= 16 +20

Δ= 36

x= 4±6/2   x'= 10/2= 5   x"= -2/2= -1

G) 4 +x(x-4)= x

    4 +x² -4x= x

    x² -5x +4= 0

Δ= (-5)² -4×1×4

Δ= 25 -16

Δ= 9

x= 5±3/2   x'= 8/2= 4   x"= 2/2 = 1

H) x×(x +3) -40= 0

    x² +3x -40= 0

Δ= 3² -4×1×(-40)

Δ= 9 +160

Δ= 169

x= -3±13/2   x'= 10/2= 5  x"= -16/2= -8