tìm x a ( 2x – 1 )^5 = 243 b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73 c, ( x + 1 )^4 = 81 . là nhân 04/09/2021 Bởi Adeline tìm x a ( 2x – 1 )^5 = 243 b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73 c, ( x + 1 )^4 = 81 . là nhân
Đáp án: $a ( 2x – 1 )^5 = 243$$⇒2x – 1= 3$$⇒2x = 4$$⇒x= 2$$b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73$ $⇒3 . ( x – 3 )^2 – 2 . 1 = 73$$⇒3 . ( x – 3 )^2= 75$$⇒( x – 3 )^2= 25$⇒\(\left[ \begin{array}{l}x – 3= -5\\x – 3= 5\end{array} \right.\) ⇒\(\left[ \begin{array}{l}x=-2\\x=8\end{array} \right.\) $c, ( x + 1 )^4 = 81 $⇒\(\left[ \begin{array}{l}⇒x + 1= 3\\⇒x + 1= -3\end{array} \right.\) ⇒\(\left[ \begin{array}{l}x=-2\\x=4\end{array} \right.\) Bình luận
a ( 2x – 1 )^5 = 243 2x – 1 = 3 2x = 4 x = 2 b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73 3 . ( x – 3 )^2 – 2 . 1 = 73 3 . ( x – 3 )^2 = 75 ( x – 3 )^2 = 25 TH1 : x – 3 = 5 x = 8 TH2 : x – 3 = -5 x = -2 c, ( x + 1 )^4 = 81 TH1 : x + 1 = 3 x = 2 TH2 : x + 1 = -3 x = -4 Bình luận
Đáp án:
$a ( 2x – 1 )^5 = 243$
$⇒2x – 1= 3$
$⇒2x = 4$
$⇒x= 2$
$b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73$
$⇒3 . ( x – 3 )^2 – 2 . 1 = 73$
$⇒3 . ( x – 3 )^2= 75$
$⇒( x – 3 )^2= 25$
⇒\(\left[ \begin{array}{l}x – 3= -5\\x – 3= 5\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=-2\\x=8\end{array} \right.\)
$c, ( x + 1 )^4 = 81 $
⇒\(\left[ \begin{array}{l}⇒x + 1= 3\\⇒x + 1= -3\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=-2\\x=4\end{array} \right.\)
a ( 2x – 1 )^5 = 243
2x – 1 = 3
2x = 4
x = 2
b, 3 . ( x – 3 )^2 – 2 . 1989^0 = 73
3 . ( x – 3 )^2 – 2 . 1 = 73
3 . ( x – 3 )^2 = 75
( x – 3 )^2 = 25
TH1 : x – 3 = 5
x = 8
TH2 : x – 3 = -5
x = -2
c, ( x + 1 )^4 = 81
TH1 : x + 1 = 3
x = 2
TH2 : x + 1 = -3
x = -4