Question

Se Ax,3=210 então x vale:

Answer 1

Resolução:
A x , 3 = 210

$An,p = \frac{n!}{(n-p)!}$

$\frac{x!}{(x-3)!}=210$

$\frac{x.(x-1).(x-2).(x-3)!}{(x-3)!} =210$

$x.(x-1).(x-2)=210$

$x^{3} -3 x^{2} +2x-210=0$

$(x-7).( x^{2} +4x+30)=0$

$x-7=0$

$x=7$

$x^{2} +4x+30=0$

$x=-2+i \sqrt{26}$

$x=-2-i \sqrt{26}$

$S = {7,-2+i \sqrt{26} ,-2+i \sqrt{26}}$

bons estudos.