`a)(10x^4-4x^3+2x):2x^2`

`=10x^4:2x^2-4x^3:2x^2+2x:2x^2`

`=5x^2-2x+1/x`

Thay `x=-1/4`, ta có:

`5*(-1/4)^2-2*(-1/4)+1:(-1/4)`

`=5*1/16+1/2+1*(-4)`

`=5/16+1/2-4`

`=-51/16`

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`b)(2x^4-x^3+2x^2):(-1/3x^2)`

`=2x^4:(-1/3x^2)-x^3:(-1/3x^2)+2x^2:(-1/3x^2)`

`=-6x^2+3x-6`

Thay `x=-1/3`, ta có:

`-6*(-1/3)^2+3*(-1/3)-6`

`=-6*1/9-1-6`

`=-2/3-7`

`=-23/3`

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`c)(3/4x^9+6/5x^7-9/10x^6):(-3/5x^4)`

`=3/4x^9:(-3/5x^4)+6/5x^7:(-3/5x^4)-9/10x^6:(-3/5x^4)`

`=-5/4x^5-2x^3+3/2x^2`

Thay `x=1`, ta có:

`-5/4*1^5-2*1^3+3/2*1^2`

`=-5/4-2+3/2`

`=-7/4`

$#ptjuoy$