a,

\(97.13+130.0,3=13.(97+10.0,3)=13.100=1300\)

b,

\(86.153-530.86= -377.86=-32422\)

a) Ta có: \(\dfrac{6x^2-8xy}{9xy-12y^2}\)

\(=\dfrac{2x\left(3x-4y\right)}{3y\left(3x-4y\right)}=\dfrac{2x}{3y}\)
b) \(\dfrac{2a^3-18a}{a^4-81}\)

\(=\dfrac{2a\left(a^2-9\right)}{\left(a^2-9\right)\left(a^2+9\right)}=\dfrac{2a}{a^2+9}\)

Em bấm vào biểu tượng \(\sum\) trên thanh công cụ và gõ phân số để mn dễ hỗ trợ nhé!

`(x^2+x-6)/(x^2+4x+3):(x^2-10x+25)/(x^2-4x-5)(x ne -1,x ne 5,x ne -3)`

`=((x-2)(x+3))/((x+1)(x+3)):(x-5)^2/((x+1)(x-5))`

`=(x-2)/(x+1):(x-5)/(x+1)`

`=(x-2)/(x-5)`

a) \(97\cdot13+130\cdot0,3\)

\(=97\cdot13+13\cdot3\)

\(=13\cdot\left(97+3\right)\)

\(=13\cdot100\)

\(=1300\)

b) \(86\cdot153-530\cdot8,6\)

\(=86\cdot153-53\cdot86\)

\(=86\cdot\left(153-53\right)\)

\(=86\cdot100\)

\(=8600\)

a) \(97.13+130.0,3\)

\(=97.13+13.3\)

\(=13\left(97+3\right)=13.100=1300\)

b) \(86.153-530.8,6\)

\(=86.153-53.86\)

\(=86.\left(153-53\right)=86.100=8600\)

\(a,=6x^2-4x-x^2-4x-4=5x^2-8x-4\\ b,=x^3+8-2\left(1-x^2\right)=x^3+8-2+2x^2=x^3+2x^2+6\\ c,=2xy+2y^2+3x^2-3xy+5=3x^2+2y^2-xy+5\)

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

\(=x\left(x^2-16\right)\)

\(=x^3-16x-\left(x^2+1\right)\left(x^2-1\right)\)

\(=x^3-16x-x^4+1\)

b) \(7x\left(4y-x\right)+4y\left(y-7x\right)-2\left(2y^2-3.5x\right)\)

\(=28xy-7x^2+4y\left(y-7x\right)-2\left(2y^2-3.5x\right)\)

\(=28xy-7x^2+4y^2-28xy-4y^2+7x\)

\(=-7x^2+7x\)

c) \(\left(3x-1\right)\left(2x-5\right)-4\left(2x^2-5x+2\right)\)

\(=6x^2-17x+5-4\left(2x^2-5x+2\right)\)

\(=6x^2-17x+5-8x^2+20x-8\)

\(=-2x^2+3x-3\)

a)  x(x+4)(x-4)-(x²+1)(x²-1)

=>x(x²-4²)-(x⁴-1²)

=>x³-16x-x⁴+1

=>-x⁴-x³-15x

b)  7x(4y-x)+4y(y-7x)-2(2y²-3.5x)

=>28xy-7x²+4y²-28xy-4y²+30x

=>-7x²+30x

c)  (3x+1)(2x-5)-4(2x²-5x+2)

=>6x²-15x+2x-5-8x²+20x-8

=>-2x²+7x-13

x - 212 - 2x + 13 = 3x + 56 - x

x - 2x - 3x + x = 212 - 13 + 56

-3x = 255

x = - 85

theo đề bài, ta có:

x-212-2x+13=3x+56-x

\(\Rightarrow\)x-2x-3x+x=212+56-13

\(\Rightarrow\)-3x=255

\(\Rightarrow\)x=\(\frac{255}{-3}\)

\(\Rightarrow\)x=-85

..

đc ko bạn

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