Toán Lớp 8: Tìm x , biết
a ( x+3)(x-1)=0
b 2x(x-5)-x+5=0
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Toán Lớp 8: Tìm x , biết
a ( x+3)(x-1)=0
b 2x(x-5)-x+5=0
Comments ( 2 )
Giải đáp:
Câu a là x = -3 hoặc x = 1
Câu b :
2x(x – 5) – (x+5) =0
2x(x – 5) – (x – 5) =0
(x-5) (2x-1) =0
x= 5 hoặc x= 1/2
a,(x+3)(x-1)=0
⇔\(\left[ \begin{array}{l}x+3=0\\x-1=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=-3\\x=1\end{array} \right.\)
Vậy x={-3;1}
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b,2x(x-5)-x+5=0
⇔2x(x-5)-(x-5)=0
⇔(x-5)(2x-1)=0
⇔\(\left[ \begin{array}{l}x-5=0\\2x-1=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=5\\x=\frac{1}{2}\end{array} \right.\)
Vậy x={5;\frac{1}{2}}