Question

Tìm số nguyên x biết: (x-7).(x+3)<0

Answer 1

Để (x-7)(x+3) < 0 thì:
+) x-7 <0 <=> x<7
x+3 >0 <=> x>-3

Hay -3<x<7 => x={-2; -1; 0; 1; 2; 3; 4; 5; 6}
+) x-7 >0 <=> x>7
x+3 <0 <=>x<-3
Hay -3>x>7 (vô lí)

Vậy x={-2; -1; 0; 1; 2; 3; 4; 5; 6}

Answer 2

S=\(\left\{1;2;3;4;5;6\right\}\)