Gọi d là ƯCLN ( 2n + 5, 3n + 7 )

\(2n+5⋮d\Rightarrow3.\left(2n+5\right)⋮d\Rightarrow6n+15⋮d\)

\(3n+7⋮d\Rightarrow2.\left(3n+7\right)⋮d\Rightarrow6n+14⋮d\)

\(\left[\left(6n+15\right)-\left(6n+14\right)\right]⋮d\)

\(\left[6n+15-6n-14\right]⋮d\)

\(\Rightarrow1⋮d\Rightarrow d=1\)

PP/ss: Hoq chắc ạ ((:

Gọi ƯCLN(2n+5,3n+7)=d

Ta có:2n+5:d,suy ra 3(2n+5)=6n+15:d

         3n+7:d suy ra 2(3n+7)=6n+14:d

Vậy (6n+15)-(6n+14):d

Nên 1:d,suy ra 2 ƯCLN của 2 số là 1

--hok tốt--

  5 + \(^{3^{x+1}}\)= 86

5 + 3\(^x\)x 3 =86

     3\(^x\)x 3  =86 - 5

     3\(^x\) x3   =81

     3\(^x\)        =81:3

     3\(^x\)        =27

     3\(^x\)        =3\(^3\)

  =>  x           =3

Vậy =3

Chắc 100% nha bạn

|x| = <4 => x = 1.2.3

Trả lời :............................................

/x/ = <4 => x = 1 . 2 . 3

Hk tốt,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a)  AB < AC 

=>  B nam giua A va C

b)  Vi B nam giua A va C nen:

BC = AC - AB = 7 - 3,5 = 3,5 (cm)

=>  AB = BC

c) B la trung diem AC vi: 

+) B nam giua A va C

+) BA = BC 

\(1+\left(-2\right)+3+\left(-4\right)+5+...+\left(-98\right)+99\)

\(=\left(1+3+5+...+99\right)+\left[\left(-2\right)+\left(-4\right)+...+\left(-98\right)\right]\)

\(=\frac{100.50}{2}+\frac{-100.49}{2}\)

\(=2500+\left(-2450\right)\)

\(=50\)

-Mơn ✖Ngáo-Picas✖ ạ ((:

Trả lời :.......................................

0,8 g/m³ = 800 kg/m³

Hk tốt,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

a)  CB = AB - AC = 4 - 1 = 3(cm)

b)  Tren tia doi BC lay D

=>  B nam giua C va D

=>  BD < CD

c)  B nam giua C va D

=>  BD = CD - BC = 6 - 3 = 3

Ta co:  BC = BD = 1/2 CD

=>  B la trung diem CD

a va b la 2 so tu nhien lien tiep, a < b

=>  b = a + 1

Goi (a;b) = d

=>  \(\hept{\begin{cases}a⋮d\\b⋮d\end{cases}}\)  hay   \(\hept{\begin{cases}a⋮d\\a+1⋮d\end{cases}}\)

=>   \(1⋮d\)

=>  \(d=\pm1\)

=>  a,b la 2 so nguyen to cung nhau