標題:

[F.4]Maths Log

發問:

how to solve 3(5^2x-1)+5^2x+1=41?

最佳解答:

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3 [5^(2x- 1)] + 5^(2x) + 1 = 41 3 [5^(2x - 1)] + 5^[1 + (2x - 1)] = 40 3 [5^(2x - 1)] + 5 [5^(2x - 1)] = 40 (3 + 5) [5^(2x - 1)] = 40 8 [5^(2x - 1)] = 40 5^(2x - 1) = 5 2x - 1 = 1 2x = 2 x = 1

其他解答:

3(52??1)+52?+1=41 ==> 3(52?)+5(52?)+5=205 ?? (multiply each term by 5) ==> 8(52?)=200 ==> 52?=25=52 ∴ 2x=2 ==> x=1|||||3 [ 5^(2x-1) ] + 5^(2x+1) = 41 or 3 [ 5^(2x) - 1 ] + 5^(2x) + 1 = 41 ?
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