Question

Fie E(x)=7(x+2)/(x-3)
Determinati multimea A={x apartine lui Z-{-5;-2;-1;1;3}| E(x) apartine lui Z

Answer 1

E(x)=7(x²-3x+2x-6)
=7x²-21x+14x-42
=7x²-7x-42
7x²-7x-42=0 | ÷7
x²-x-6=0
∆=1+24=25=>√∆=5
x=(1+5)÷2=6÷2=3
x=(1-5)÷2=(-4)÷2= -2

A={-2;3}