`R(x)=(3x+2)(3x-5)(x-1)(9x+10)+24x^2`
`R(x)=[(3x+2)(3x-5)][(x-1)(9x+10)]+24x^2`
`R(x)=(9x^2-15x+6x-10)(9x^2+10x-9x-10)+24x^2`
`R(x)=(9x^2-9x-10)(9x^2+x-10)+24x^2`
`R(x)=(9x^2-4x-10-5x)(9x^2-4x-10+5x)+24x^2`
`R(x)=(9x^2-4x-10)^2-25x^2+24x^2`
`R(x)=(9x^2-4x-10)^2-x^2`
`R(x)=(9x^2-4x-10-x)(9x^2-4x-10+x)`
`R(x)=(9x^2-5x-10)(9x^2-3x-10)`
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`K(x)=(6x+5)^2(3x+2)(x+1)-35`
`K(x)=(36x^2+60x+25)(3x^2+5x+2)-35`
Đặt `3x^2+5x+2=a -> 36x^2+60x+25=12a+1`
`K(x)=a(12a+1)-35`
`K(x)=12a^2+a-35`
`K(x)=12a^2-20a+21a-35`
`K(x)=4a(3a-5)+7(3a-5)`
`K(x)=(3a-5)(4a+7)`
Thay `a=3x^2+5x+2` vào K(x) thì:
`K(x)=[3(3x^2+5x+2)-5][4(3x^2+5x+2)+7]`
`K(x)=(9x^2+15x+6-5)(12x^2+20x+8+7)`
`K(x)=(9x^2+15x+1)(12x^2+20x+15)`