Tìm x, biết: $^{2017}$ $^{2017}$
(5$x^{2}$ – 25)$^{2018}$ = (-20)$^{2018}$
Tìm x, biết: $^{2017}$ $^{2017}$ (5$x^{2}$ – 25)$^{2018}$ = (-20)$^{2018}$
By Alaia
By Alaia
Tìm x, biết: $^{2017}$ $^{2017}$
(5$x^{2}$ – 25)$^{2018}$ = (-20)$^{2018}$
` (5x^{2} – 25)^{2018} = (-20)^{2018} `
` <=> ` \(\left[ \begin{array}{l}5x^{2}-25=20\\5x^{2}-25=-20\end{array} \right.\)
` <=> ` \(\left[ \begin{array}{l}5x^{2}=45\\5x^{2}=5\end{array} \right.\)
` <=> ` \(\left[ \begin{array}{l}x^{2}=9\\x^{2}=1\end{array} \right.\)
` <=> ` \(\left[ \begin{array}{l}x=3\\x=-3\\x=1\\x=-1\end{array} \right.\)
Vậy ` x = 3 ` ; ` x =-3 ` ; ` x = 1 ` hoặc `x = -1 `
$(5x^2-25)^{2018}=(-20)^{2018}$
$Th1: 5x^2-25=-20$
$⇒5x^2=5$
$⇒x^2=1$
$⇒$\(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\)
$Th2: 5x^2-25=20$
$⇒5x^2=45$
$⇒x^2=9$
$x=$\(\left[ \begin{array}{l}x=3\\x=-3\end{array} \right.\)
Vậy x=1; x=-1; x=3; x=-3