a,x³-0,25x=0
⇒x(x²-0,25)=0
⇒x(x-0,5)(x+0,5)=0
⇒\(\left[ \begin{array}{l}x=0\\x-0,5=0\\x+0,5=0\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=0\\x=0,5\\x=-0,5\end{array} \right.\)
b,x⁴+2x³+x²=0
⇒x²(x²+2x+1)=0
⇒x²(x+1)²=0
⇒\(\left[ \begin{array}{l}x=0\\x=-1\end{array} \right.\)
c,x³-1=0
⇒x³=1
⇒x³=1³
⇒x=1
d,6x²-7x+2=0
⇒(6x²-3x)-(4x-2)=0
⇒6x(x-$\frac{1}{2}$ )-4(x-$\frac{1}{2}$ )=0
⇒(x-$\frac{1}{2}$ )(6x-4)=0
⇒\(\left[ \begin{array}{l}x=\frac{1}{2}\\x=\frac{2}{3}\end{array} \right.\)
Bài 2:
x²(x-5)+x²-4x-5=0
⇒x²(x-5)+(x²-5x)+(x-5)=0
⇒x²(x-5)+x(x-5)+(x-5)=0
⇒(x-5)(x²+x+1)=0
Ta có: x²+x+1>0 ∀x
⇒x-5=0
⇒x=5
b,x⁶-1=0
⇒(x³+1)(x³-1)=0
⇒\(\left[ \begin{array}{l}x=-1\\x=1\end{array} \right.\)
Chúc bạn học tốt nhé! ^^
