dễ ợt. cô giáo hướng dẫn cho mình là 56 người

5x+26=6

=>5x=6-26

5x=-20

=>x=-4

\(\dfrac{3\left(3x-7\right)}{6}+\dfrac{2\left(x+1\right)}{6}=-16\)

=> \(\dfrac{3\left(3x-7\right)+2\left(x+1\right)}{6}=-16\)

=> 3(3x-7)+2(x+1)=-16.6=-96

=> 9x-21+2x+2+96=0

=> 11x+77=0

=> 11x=-77

=> x=-7

ok tớ tick rồi cậu tick tớ đi

N?

P=(chieu dai + chieu rong).2

=> 3.chieu dai=2.chieu dai + 2.chieu rong

=> 3.chieu dai - 2.chieu dai=2.chieu rong

=> chieu dai = 2.chieu rong

Vay chu vi gap 3 lan chieu dai thi chieu dai se gap 2 lan chieu rong

chu vi hinh gi

PTHH: X+2HCl--> XCL₂+H₂

n_HCl=4,38:36,5=0,12(mol)

Theo PTHH: n_X=1/2.n_HCl=1/2.0,12=0,06(mol)

=> M_X=3,36:0,06=56(g/mol)

=> X la Fe

Vi x²+2≥2>0 nen : pt⇔ x²+/x-1/=x²+2

=> /x-1/=2

=> \(\left[{}\begin{matrix}x-1=2\\x-1=-2\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}x=2+1=3\\x=-2+1=-1\end{matrix}\right.\)

Goi d la UCLN(2n+1,2n(n+1)) nen tao co:

\(\left\{{}\begin{matrix}2n+1⋮d\\2n\left(n+1\right)⋮d\end{matrix}\right.\)

=> \(\left\{{}\begin{matrix}2n+1⋮d\\n\left(2n+1\right)+n⋮d\end{matrix}\right.\)

=> n⋮d

=> 1.n⋮d => 1⋮d

=> dpcm