Bài 1: Lũy thừa

Để \(13 \vdots (2n - 1)\)

thì \((2n - 1) \epsilon Ư(13)\)

\(Ư (13) = \left \{ - 13; - 1 ; 1; 13 \right \}\)

Do đó:

2n - 1 = - 13 => n = - 6

2n - 1 = - 1 => n = 0

2n - 1 = 1 => n = 1

2n - 1 = 13 => n = 7

Vậy \(n \epsilon \left \{ - 6;0;1;7 \right \}\) thì \(13 \vdots (2n - 1)\)

13chia hết cho (2n - 1)

⇒2n-1 ∈ Ư(13)

Ư(13)={-1;1;-13;13}

➤ n ∈ {0;1;-6;7}

\(\left(1-\dfrac{1}{2}\right)\):\(\left(1-\dfrac{1}{3}\right)\):\(\left(1-\dfrac{1}{4}\right)\):\(\left(1-\dfrac{1}{5}\right)\):\(\left(1-\dfrac{1}{6}\right)\):\(\left(1-\dfrac{1}{7}\right)\)

=\(\left(\dfrac{2-1}{2}\right)\):\(\left(\dfrac{3-1}{3}\right)\):\(\left(\dfrac{4-1}{4}\right)\):\(\left(\dfrac{5-1}{5}\right)\):\(\left(\dfrac{6-1}{6}\right)\)

=\(\dfrac{1}{2}\):\(\dfrac{2}{3}\):\(\dfrac{3}{4}\):\(\dfrac{4}{5}\):\(\dfrac{5}{6}\)

=\(\dfrac{1.\left(3.4.5\right)6}{\left(3.4.5\right)\left(2.2\right)}\)

=\(\dfrac{6}{2.2}=\dfrac{3}{2}\)

@Ngô Tấn Đạt

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\(\left(x-2\right)^2=x^2-2.x.2+2^2=x^2-4x+4\)

Nguyễn NamTrần QNguyễn Thanh HằngHoàng NNgPhạm Hoàng Giangô Thu TranggAkai Harumaọc Ace LHung nguyenegonaAnhuốc LFairy Tailộc

a) \(3^{x + 1} = 81\)

\(3^{x + 1} = 3^{4}\)

x + 1 = 4

x = 3

Vậy ..............

b) \(3^{x}.9^{2}= 729\)

\(3^{x}= 729 : 81 = 9\)

\(3^{x}= 3^{2}\)

=> x = 2

Vậy ................

c) \((x^{2})^{3}= 4096\)

\(x^{6}= 4096\)

\(x^{6}= 4^{6}\)

=> x = 4

Vậy ................