Toán Lớp 8: Tìm X bt;
b/ x(x+5)= x+5
giúp!!!!!!!!!!!!!
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Toán Lớp 8: Tìm X bt;
b/ x(x+5)= x+5
giúp!!!!!!!!!!!!!
Comments ( 2 )
Giải đáp:
x = – 5 ; x = 1
Lời giải và giải thích chi tiết:
b)
x(x + 5) = x + 5
x(x + 5) – (x + 5) = 0
(x + 5)(x – 1) = 0
=> [(x + 5 = 0),(x – 1 = 0):}
=> [(x = – 5),(x = 1):}
Vậy x = – 5 ; x = 1
#SunHee
Answer
x . (x + 5) = x + 5
=> x^2 + 5x = x + 5
=> x^2 + 5x – x – 5 = 0
=> x^2 + 4x – 5 = 0
=> (x – 1) . (x + 5) = 0
=> $\left[\begin{matrix} x-1=0\\ x+5=0\end{matrix}\right.$
=> $\left[\begin{matrix} x=0+1\\ x=0-5\end{matrix}\right.$
=> $\left[\begin{matrix} x=1\\ x=-5\end{matrix}\right.$
Vậy x \in {1 ; -5}