Ta có:

2015²⁰¹⁷ + 2017²⁰¹⁵

= 2015²⁰¹⁷ + 1 + 2017²⁰¹⁵ - 1

= (2015²⁰¹⁷ + 1²⁰¹⁷) + (2017²⁰¹⁵ - 1²⁰¹⁵)

Do 2015²⁰¹⁷ + 1²⁰¹⁷ luôn chia hết cho 2015 + 1 = 2016; 2017²⁰¹⁵ - 1²⁰¹⁵ luôn chia hết cho 2017 - 1 = 2016

=> (2015²⁰¹⁷ + 1²⁰¹⁷) + (2017²⁰¹⁵ - 1²⁰¹⁵) chia hết cho 2016

=> 2015²⁰¹⁷ + 2017²⁰¹⁵ chia hết cho 2016 (đpcm)

TAU KHONG BIET

\(2015^{2017}+2017^{2015}=\left(2015^{2017}+1\right)+\left(2017^{2015}-1\right)=A\left(2015+1\right)+B\left(2017-1\right)=2016A+2016B=2016\left(A+B\right)\)Luôn chia hết cho 2016

Vậy ta có điều phải chứng minh.

$\textbf{1.}$

Ta có $5^{2017}+5^{2015}=5^{2015}(5^2+1)$

$=5^{2015}\cdot26$

$=5^{2015}\cdot13\cdot2.$

Vì $13\mid13\cdot2$ nên $13\mid\left(5^{2017}+5^{2015}\right).$

Vậy $5^{2017}+5^{2015}$ chia hết cho $13.$

$\textbf{2.}$

Giả sử $a^{2014}+b^{2015}+c^{2016}\vdots6.$

Ta có $a^{2016}-a^{2014}=a^{2014}(a^2-1)$

$=a^{2014}(a-1)(a+1).$

Vì $a(a-1)(a+1)\vdots6$ nên $a^{2014}(a-1)(a+1)=a^{2013}\cdot a(a-1)(a+1)\vdots6.$

Suy ra $a^{2016}\equiv a^{2014}\pmod6.$

Tương tự, $b^{2017}-b^{2015}=b^{2015}(b^2-1)$

$=b^{2014}\cdot b(b-1)(b+1)\vdots6,$ nên $b^{2017}\equiv b^{2015}\pmod6.$

Lại có $c^{2018}-c^{2016}=c^{2016}(c^2-1)$

$=c^{2015}\cdot c(c-1)(c+1)\vdots6,$ nên $c^{2018}\equiv c^{2016}\pmod6.$

Cộng ba đồng dư trên, $a^{2016}+b^{2017}+c^{2018}\equiva^{2014}+b^{2015}+c^{2016}\equiv0\pmod6.$

Vậy $a^{2016}+b^{2017}+c^{2018}$ chia hết cho $6.$

Chưa ai  giải thì thui 

MK cũng bó tay

Chúc bn hok t

:) hihi

\(\frac{x+5}{2015}+\frac{x+4}{2016}+\frac{x+3}{2017}=\frac{x+2015}{5}+\frac{x+2016}{4}+\frac{x+2017}{3}\)

\(\Leftrightarrow\frac{x+5}{2015}+\frac{x+4}{2016}+\frac{x+3}{2017}-\frac{x+2015}{5}-\frac{x+2016}{4}-\frac{x+2017}{3}=0\)

\(\Leftrightarrow\left(\frac{x+5}{2015}+1\right)+\left(\frac{x+4}{2016}+1\right)+\left(\frac{x+3}{2017}+1\right)-\left(\frac{x+2015}{5}+1\right)-\left(\frac{x+2016}{4}+1\right)\)

\(-\left(\frac{x+2017}{3}+1\right)=0\)

\(\Leftrightarrow\frac{x+2020}{2015}+\frac{x+2020}{2016}+\frac{x+2020}{2017}-\frac{x+2020}{5}-\frac{x+2020}{4}-\frac{x+2020}{3}=0\)

\(\Leftrightarrow\left(x+2020\right)\left(\frac{1}{2015}+\frac{1}{2016}+\frac{1}{2017}-\frac{1}{5}-\frac{1}{4}-\frac{1}{3}\right)=0\)

\(\Leftrightarrow x+2020=0\left(\frac{1}{2015}+\frac{1}{2016}+\frac{1}{2017}-\frac{1}{5}-\frac{1}{4}-\frac{1}{3}\ne0\right)\)

<=> x=-2020

Vậy x=-2020

Giải phương trình: (3x-2)(x-1)^2(3x+8)=-16

Lời giải:

Ta có:

\(A=2015^{2017}+2017^{2015}=2015^{2017}+1+2017^{2015}-1\)

Theo khai triển hằng đẳng thức:

\(2015^{2017}+1=2015^{2017}+1^{2017}=(2015+1)(2015^{2016}-2015^{2015}+....-2015+1)\vdots (2015+1)\)

\(\Leftrightarrow 2015^{2017}+1\vdots 2016\) (1)

Và: \(2017^{2015}-1=2017^{2015}-1^{2015}=(2017-1)(2017^{2014}+2017^{2013}+...+2017+1)\vdots (2017-1)\)

\(\Leftrightarrow 2017^{2015}-1\vdots 2016\) (2)

Từ (1),(2) suy ra \(A=2015^{2017}+2017^{2015}\vdots 2016\) (đpcm)

Nếu đúng tick em nha

2015^2017+2017^2015

=2015^2017+2017^2015-1

=(2015^2017+1^2017)+(2017^2015-1^2015)

Do 2015^2017+1^2017\(⋮\)2015+2=2016

2017^2015-1^2015\(⋮\)2017-1=2016

Vậy (2015^2017+2017^2015)\(⋮\)2016

Tick nha !