Question

9- Na equação binomial ( ×sobre 2 )= × + 9 o valor de x é?
( 2 )


A- 6

B-7

C-8

D-9

Answer 1

$\left(\begin{array}{ccc}x\\2\\\end{array}\right)=x+9=\ \textgreater \ \frac{x!}{2!(x-2)!} =x+9=\ \textgreater \ \frac{x(x-1)(x-2)!}{2.(x-2)!} =x+9=\ \textgreater \ \\ x(x-1)=2(x+9)=\ \textgreater \ x^2-x-2x-18=0=\ \textgreater \ x^2-3x-18=0 \\ =\ \textgreater \ D=9+4.18=\ \textgreater \ D=81=\ \textgreater \ x=(3-9)/2=-3(nao) \\ oux=(3+9)/2=6$