Răspuns:
Explicație pas cu pas:
a) x³+x²+6x=x(x²+x+6)
x^5-9x³=x³(x²-9)=x³(x-3)(x+3)
b) E(x)=[3(x+3)+(x+1)(x-3)]/(x²-9)· x³(x²-9)/x(x²+x+6)=
=(3x+9+x²-2x-3)·x²/(x²+x+6)=(x²+x+6)·x²/(x²+x+6)=x²
x∈R\{±3,0}
c)E(x)=(x-5)(x+3) ⇒x²=x²-2x-15 ⇒2x+15=0 ⇒x=-15/2
