Toán Lớp 6: 86 : [ 2 . (2x -1)^2 – 7] + 4^2 = 2 .3^2
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Toán Lớp 6: 86 : [ 2 . (2x -1)^2 – 7] + 4^2 = 2 .3^2
Tìm x
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Giải đáp:
86:[2.(2x−1)^2−7]+4^2=2.3^2
-> 6:[2.(2x−1)^2−7]+16= 18
-> 86:[2.(2x−1)^2−7]=18−16
-> 86:[2.(2x−1)^2−7]= 2
-> 2.(2x−1)^2−7 = 43
-> 2.(2x−1)^2 = 50
-> (2x−1)^2 = 25
-> $\left[\begin{matrix} 2x – 1 = 5\\ 2x – 1 = -5\end{matrix}\right.$
-> $\left[\begin{matrix} x = 3\\x = -2\end{matrix}\right.$
Vậy x ∈ {3; -2}
$#dariana$
Giải đáp:
Lời giải và giải thích chi tiết:
86 : [2.(2x-1)^2-7]+4^2 = 2.3^2
86 : [2.(2x-1)^2-7] +16 = 16
86 : [2.(2x-1)^2 – 7 ] = 16-16
86 : [2.(2x-1)^2 – 7 ] = 0
2.(2x-1)^2-7 = 0
2.(2x-1)^2 = 7
(2x-1)^2 = 7 : 2
(2x-1)^2 = 7/2
2x-1 = 7/2
2x=9/2
x=9/2 : 2
x=9/4
2x-1 = -7/2
2x=-7/2 + 1
2x=-5/2
x=-5/2 : 2
x=-5/4
vậy x\in{9/4;-5/4}