Question

resolva as equaçao
Cx,2=15

Answer 1

x!/2!(x-2)!=15

x(x-1)(x-2)!/2!(x-2)!=15

x(x-1)/2!=15

x²-x=30

x²-x-30=0

x'=[1+(1+120)¹/²]/2=6

x"=[1-(1+120)¹/²]/2<0 ->ñ existe fatorial<0

Resposta:{6}

Answer 2

Cx,2 = x!/2!(x - 2)!

15 = x!/2!(x - 2)!

15 = [x.(x-1).(x-2)!]/2(x-2)!

15 = x.(x-1)/2

30 = x.(x-1)

x² - x - 30 = 0

Δ = (-1)² - 4(1)(-30)
Δ = 1 + 120 = 121
√Δ = √121 = 11

x' = (1 + 11)/2 = 12/2 = 6

x'' = (1 - 11)/2 = -10/2 = -5 (não serve)

Resposta: x = 6

Espero ter ajudado.