Question

ajutatima va rog cu un exercitiu la mate

Answer 1

$DVA:x \geq 2 \\ \frac{x!}{(x-2)!}* \frac{x!}{(x-1)!} =4 \\ \frac{(x-2)!(x-1)x}{(x-2)!} * \frac{(x-1)!*x}{(x-1)!} =4 \\ (x-1)*x*x=4 \\ x^3- x^{2} -4=0 \\ x^3-8- x^{2} +4=0 \\ (x^3-8)-( x^{2} -4)=0 \\ (x-2)( x^{2} +2x+4)+(x-2)(x+2)=0 \\ (x-2)( x^{2} +3x+6)=0 \\ x-2=0 \\ x=2$
S={2}