a)x+5x²=0
⇔x(1+5x)=0⇔x(1+5x)=0
⇔x=0⇔x=0
1+5x=01+5x=0
⇔x=0⇔x=0
5x=−15x=-1
⇔x=0⇔x=0
x=−15x=-15
b)2x3−8x=0b)2x3-8x=0
⇔2x(x−4)=0⇔2x(x-4)=0
⇔2x=0⇔2x=0
x−4=0x-4=0
⇔x=0⇔x=0
x=4
c)x(x-2)+3(x-2)=0
(x-2) (x+3)=0
⇒\(\left[ \begin{array}{l}x-2=0\\x+3=0\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=2\\x=-3\end{array} \right.\)
Vậy x=2 hoặc x=-3
d)2(x+5)x²-5x=0
2(x+5)-x(x+5)=0
(x+5)(x-2)=0
⇒\(\left[ \begin{array}{l}x+5=0\\x-2=0\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=-5\\x=2\end{array} \right.\)
vậy x=-5hoawcj x=2
CHÚC BẠN HỌC TỐT
