đg `+` rồi chuyển sang `-` luôn v❔

\(\left(x^2-4\right)\left(2x+x+3\right)\\ =\left(x^2-4\right)\left(3x+3\right)\\ =3x^3+3x^2-12x-12\\ =3x^2\left(x+1\right)-12\left(x+1\right)\\ =\left(x+1\right)\left(3x^2-12\right)\\ =3\left(x+1\right)\left(x^2-4\right)\\ =3\left(x+1\right)\left(x-2\right)\left(x+2\right)\)

7/5 no 7/3 con uii:))

`7/5 x -2/3 = -4/3x -1/4`

`=> 7/5x +4/3x = -1/4 +2/3`

`=> (7/5 +4/3) x = -3/12 + 8/12`

`=> 41/15 x= 5/12`

`=> x= 5/12 : 41/15`

`=> x= 5/12 xx 15/41`

`=>x=41/36`

Ta có :

\(5^{199}< 5^{200}=5^{2\cdot100}=25^{100}\)

\(3^{300}=3^{3\cdot100}=27^{100}\)

Mà \(25^{100}< 27^{100}\Rightarrow5^{199}< 3^{300}\)

Vậy \(\dfrac{1}{3^{300}}>\dfrac{1}{5^{199}}\)

Câu `11`

`a, 9/4 + (-7)/6 *3/7`

`= 9/4 + (-21)/42`

`= 9/4 +(-1/2)`

`= 9/4 + (-2/4)`

`= 7/4`

`b, -3/8 *1/9 +1/9 *(-13)/8`

`= 1/9 * (-3/8 -13/8)`

`= 1/9 * (-16)/8`

`= 1/9 * (-2)`

`= -2/9`

`c, -1/7 +6/7 *(0,5-1/3)`

`=  -1/7 +6/7 * (1/2-1/3)`

`=  -1/7 +6/7 *1/6`

`=-1/7 + 6/42`

`=-1/7 +1/7`

`=0`

`d, (-1/4)^2 * 4/11 +7/11*(-1/4)^2`

`=(-1/4)^2 *(4/11+7/11)`

`=(-1/4)^2 * 11/11`

`= 1/16*1`

`=1/16`