a) \(\left(x-4\right)\left(x-7\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-4=0\\x-7=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=4\\x=7\end{array}\right.\)
b) \(x\left(x+3\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x+3=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x=-3\end{array}\right.\)
c) \(\left(x-2\right)\left(5-x\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-2=0\\5-x=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=2\\x=5\end{array}\right.\)
d) \(\left(x-1\right)\left(x^2+1\right)=0\)
\(\Leftrightarrow x-1=0\) ( Vì \(x^2+1>0\) )
\(\Leftrightarrow x=1\)
a)
\(\left(x-4\right)\left(x-7\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=4\\x=7\end{array}\right.\)
Vậy x = 4 ; x = 7
b)
\(x\left(x+3\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x=-3\end{array}\right.\)
Vậy x = 0 ; x = - 3
c)
\(\left(x-2\right)\left(5-x\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=2\\x=5\end{array}\right.\)
Vậy x = 2 ; x = 5
d)
\(\left(x-1\right)\left(x^2+1\right)=0\)
Mà \(x^2+1\ge1\)
=> x = - 1
Vậy x = - 1
a, \(\left(x-4\right).\left(x-7\right)=0\)
\(\Rightarrow x-4=0\) hoặc \(x-7=0\)
+) \(x-4=0\Rightarrow x=4\)
+) \(x-7=0\Rightarrow x=7\)
Vậy x = 4 hoặc x = 7
b, \(x.\left(x+3\right)=0\)
\(\Rightarrow x=0\) hoặc \(x+3=0\)
+) \(x+3=0\Rightarrow x=-3\)
Vậy x = 0 hoặc x = -3
c, \(\left(x-2\right).\left(5-x\right)=0\)
\(\Rightarrow x-2=0\) hoặc \(5-x=0\)
+) \(x-2=0\Rightarrow x=2\)
+) \(5-x=0\Rightarrow x=5\)
Vậy x = 2 hoặc x = 5
d, \(\left(x-1\right).\left(x^2+1\right)=0\)
\(\Rightarrow x-1=0\) hoặc \(x^2+1=0\)
+) \(x-1=0\Rightarrow x=1\)
+) \(x^2+1=0\Rightarrow x^2=-1\Rightarrow\) không có giá trị x thỏa mãn đề bài.
Vậy x = 1 hoặc không có giá trị x thỏa mãn đề bài
\(\text{a) (x-4)(x-7)=0}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x-4=0\\x-7=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0+4\\x=0+7\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=4\\x=7\end{array}\right.\)
\(\text{b) x.(x+3)=0}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x+3=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x=0-3=-3\end{array}\right.\)
\(\text{Vậy}\left[\begin{array}{nghiempt}x=0\\x=-3\end{array}\right.\)
\(\text{c)(x-2)(5-x)=0}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x-2=0\\5-x=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0+2\\x=5-0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=2\\x=5\end{array}\right.\)
\(\text{d) (x-1).(x^2 +1)=0}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x-1=0\\x^2+1=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0+1=1\\x^2=0-1=-1\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=1\\x\in\varnothing\end{array}\right.\)
\(\text{Vậy x=1}\)