\(8,1-\left(x-6\right)=4\left(2-2x\right)\)

\(\Leftrightarrow1-x+6=8-8x\)

\(\Leftrightarrow-x+8x=8-1-6\)

\(\Leftrightarrow7x=1\)

\(\Leftrightarrow x=\dfrac{1}{7}\)

\(9,\left(3x-2\right)\left(x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-2=0\\x+5=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-5\end{matrix}\right.\)

\(10,\left(x+3\right)\left(x^2+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x^2+2=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\varnothing\end{matrix}\right.\)

`8)1-(x-5)=4(2-2x)`

`<=>1-x+5=8-6x`

`<=>5x=2<=>x=2/5`

`9)(3x-2)(x+5)=0`

`<=>[(x=2/3),(x=-5):}`

`10)(x+3)(x^2+2)=0`

  Mà `x^2+2 > 0 AA x`

 `=>x+3=0`

`<=>x=-3`

`11)(5x-1)(x^2-9)=0`

`<=>(5x-1)(x-3)(x+3)=0`

`<=>[(x=1/5),(x=3),(x=-3):}`

`12)x(x-3)+3(x-3)=0`

`<=>(x-3)(x+3)=0`

`<=>[(x=3),(x=-3):}`

`13)x(x-5)-4x+20=0`

`<=>x(x-5)-4(x-5)=0`

`<=>(x-5)(x-4)=0`

`<=>[(x=5),(x=4):}`

`14)x^2+4x-5=0`

`<=>x^2+5x-x-5=0`

`<=>(x+5)(x-1)=0`

`<=>[(x=-5),(x=1):}`

\(11,=>\left[{}\begin{matrix}5x-1=0\\x^2-9=0\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=3\\x=-3\end{matrix}\right.\\ 12,=>\left(x+3\right)\left(x-3\right)=0\\ =>\left[{}\begin{matrix}x+3=0\\x-3=0\end{matrix}\right.=>\left[{}\begin{matrix}x=-3\\x=3\end{matrix}\right.\\ 13,=>x\left(x-5\right)-4\left(x-5\right)=0\\ =>\left(x-4\right)\left(x-5\right)=0\\ =>\left[{}\begin{matrix}x-4=0\\x-5=0\end{matrix}\right.=>\left[{}\begin{matrix}x=4\\x=5\end{matrix}\right.\)

\(14,=>x^2+5x-x-5=0\\ =>x\left(x+5\right)-\left(x+5\right)=0\\ =>\left(x-1\right)\left(x+5\right)=0\\ =>\left[{}\begin{matrix}x-1=0\\x+5=0\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)

a) \(1+\left(-3\right)+5+\left(-7\right)+9+\left(-11\right)\\ =\left(1+5+7\right)-\left(3+7+11\right)\\ =14-21\\ =-7\)

b) \(\left(-2\right)+4+\left(-6\right)+8+\left(-10\right)+12\\ =\left(4+8+12\right)-\left(2+6+10\right)\\ =24-18\\ =6\)

a)( -11) .(8.9)= (-11) .8 - (-11) .9= 11

b) (-12).10 - (-9) . 10= [ -12 - (-9) ] . 10 = -30

a) \(\left(-11\right)\cdot\left(8-9\right)=\left(-11\right)\cdot8-\left(-11\right)\cdot9=11\)

b) \(\left(-12\right)\cdot10-\left(-9\right)\cdot10=\left[-12-\left(-9\right)\right]\cdot10=-30\)

a) ( -11 ) . ( 8 - 9 ) = ( -11 ).8 - (-11).9 = 11

b) ( -12 ) . 10 - ( - 9 ) .10 = [ - 12 - ( -9 )] . 10 = -30

a)

\(5+\left(-7\right)+9+\left(-11\right)+13+\left(-15\right)\)

\(=\left[5+\left(-7\right)\right]+\left[9+\left(-11\right)\right]+\left[13+\left(-15\right)\right]\)

\(=\left(-2\right)+\left(-2\right)+\left(-2\right)=-6\)

b)

\(\left(-6\right)+8+\left(-10\right)+12+\left(-14\right)+16\)

\(=\left[\left(-6\right)+8\right]+\left[\left(-10\right)+12\right]+\left[\left(-14\right)+16\right]\)

\(=2+2+2=6\)

\(=\frac{21.273.1333.4161.10101}{91.651.2451.6643.14763}\)

\(=\frac{3.7.13.21.31.43.73.57.91.111}{7.13.21.31.43.57.73.91.111.133}=\frac{3}{133}\)

Tuy nhiên cách làm trên phải có máy tính mới làm đc: 

Có thể sử dụng công thức:

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

Sau đó phân h:

\(2^4+2^2+1=\left(2^2+2+1\right)\left(2^2-2+1\right)=7.3\)

\(4^4+4^2+1=\left(4^2+4+1\right)\left(4^2-4+1\right)=21.13\)

....Tiếp tực làm thì sẽ ra đc kết quả:

\(=\frac{3.7.13.21.31.43.73.57.91.111}{7.13.21.31.43.57.73.91.111.133}=\frac{3}{133}\)

1. A = (-2)(-3) - 5.|-5| + 125.\(\left(-\dfrac{1}{5}\right)^2\)
= 6 - 25 + 125.\(\dfrac{1}{25}\)
= -19 + 5
= -14
@Shine Anna

Đăng ít thôi

1. B = (-3).|-7| - (-4).|5| + \(\dfrac{1}{3}.\left|-9\right|\)
= -21 + 20 + 3
= 2
@Shine Anna