Question

TÌM X , BIẾT :

 

C. ( x - 1 )⁵ - ( x - 1 )⁴ = 0 

D. ( 3x - 7 )⁸ = ( 3x - 7 )⁶

E. ( 2x - 5 )⁹ = ( 2x - 5 )⁶

Answer 1

c)

\(\Rightarrow\left(x-1\right)^5=\left(x-1\right)^4\)

Vì 5 mũ lẻ

\(\Rightarrow\left[\begin{array}{nghiempt}x-1=0\\x-1=1\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=1\\x=2\end{array}\right.\)

d)

Vì 8 và 6 mũ chẵn

\(\Rightarrow\left[\begin{array}{nghiempt}3x-7=0\\3x-7=1\\3x-7=-1\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}3x=7\\3x=8\\3x=6\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{7}{3}\\x=\frac{8}{3}\\x=2\end{array}\right.\)

e)

Vì 9 mũ lẻ

\(\Rightarrow\left[\begin{array}{nghiempt}2x-5=0\\2x-5=1\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=3\end{array}\right.\)

Answer 2

Answer 3

\(C,\left(x-1\right)^5-\left(x-1\right)^4=0\)
\(\Leftrightarrow\left(x-1\right)^4\left(x-1-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)^4\left(x-2\right)\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-1=0\\x-2=0\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=1\\x=2\end{array}\right.\)