bài tập toán

Question

Tìm x, biết:

a) 5x(x  -2000) - x + 2000 = 0;

b) x³ – 13x = 0

Answer 1

a)5x(x−2000)−x+2000=05x(x−2000)−(x−2000)=0(x−2000)(5x−1)=0⇒[x−2000=05x−1=0⇒[x=2000x=15a)5x(x−2000)−x+2000=05x(x−2000)−(x−2000)=0(x−2000)(5x−1)=0⇒[x−2000=05x−1=0⇒[x=2000x=15

Vậy x=15x=15 hoặc x=2000x=2000

b)x3−13x=0x(x2−13)=0⇒[x=0x2−13=0⇒[x=0x=±√13b)x3−13x=0x(x2−13)=0⇒[x=0x2−13=0⇒[x=0x=±13

Vậy x=0x=0 hoặc x=±√13