vi khi bai toan dun

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

1 + 1 = 2 đếm ngón tay thì bằng 5

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

a, 5.4² - 27 : 3²

= 5 . 16 - 27 : 9

= 80 - 3

= 77

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

77.................................................

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

x = 1,2,3,4,6,12

x = 1 , 2 , ,3 , 4 , 6 , 12 nha

x-<17-x>=x-7

chịu

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

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