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1/5=5/25;5/25=25/125;25/125=125/625
1/25=5/125;5/125=25/625
1/125=5/625
Mình chỉ nghĩ được thế thôi:)))
\(\left(\frac{x^2+3x}{x^3+3x^2+9x+27}+\frac{3}{x^2+9}\right):\left(\frac{1}{x-3}-\frac{6x}{x^3-3x^2+9x-27}\right)\)
\(=\left(\frac{x\left(x+3\right)}{\left(x+3\right)\left(x^2+9\right)}+\frac{3}{x^2+9}\right):\left(\frac{1}{x-3}-\frac{6x}{\left(x-3\right)\left(x^2+9\right)}\right)\)
\(=\left(\frac{x}{x^2+9}+\frac{3}{x^2+9}\right):\left(\frac{x^2+9-6x}{\left(x-3\right)\left(x^2+9\right)}\right)=\frac{x+3}{x^2+9}:\frac{x^2+9-6x}{\left(x-3\right)\left(x^2+9\right)}\)
\(=\frac{\left(x+3\right)\left(x-3\right)\left(x^2+9\right)}{\left(x^2+9\right)\left(x^2-6x+9\right)}=\frac{\left(x+3\right)\left(x-3\right)}{\left(x-3\right)\left(x-3\right)}=\frac{x+3}{x-3}\)
b) \(Voix>0\Rightarrow P\ne\varnothing\)(mk ko chac)
c) \(P\inℤ\Leftrightarrow x+3⋮x-3\Leftrightarrow x-3\in\left\{-1;-2;-3;-6;1;2;3;6\right\}\)
sau do tinh
cau nay la toan lp 8 nha
( 123 . 456 - 23 . 16 ) . ( 12 . 9 - 4 . 27)
= ( 56088 - 368) . ( 108 - 108 )
= 55720 . 0
= 0
( 123 x 456 - 23 x 16 ) x ( 12 x 9 -4 x 27 )
=( 123 x 456 - 23 x 16 ) x (108 -108)
=( 123 x 456 - 23 x 16 ) x 0=0
( 123 * 456 - 23 * 46) * (12 * 9 - 4 * 27) = 55030 * 0
= 0.
`x/27 =-5/9`
`=> 9x=27.(-5)`
`=>9x= -135`
`=>x=-135:9`
`=>x= -15`
\(\dfrac{x}{27}=-\dfrac{5}{9}\)
Suy ra :
\(9\times x=-5\times27\)
\(\Leftrightarrow9\times x=-135\)
\(\Leftrightarrow x=-135:9\)
\(\Leftrightarrow x=-15\)