Toán chứng minh: `x^3-9x^2+30x-20+8y^3+12y^2+12y-12=(x-3)^3+(2y+1)^3+3(x+2y-2)` 11/07/2021 By Ximena chứng minh: `x^3-9x^2+30x-20+8y^3+12y^2+12y-12=(x-3)^3+(2y+1)^3+3(x+2y-2)`
`#DyHungg` `x³-9x²+30x-20+8y³+12y²+12y-12` `=(x³-9x²+27x-27)+(8y³+12y²+6y+1)+(3x+6y-6)` `=(x-3)³+(2y+1)³+3(x+2y-2)` `⇒đpcm` Reply
`VP=x³-9x²+30x-20+8y³+12y²+12y-12` `=x³-9x²+30x-32+8y³+12y²+12y` `=x³-9x²+27x+3x-27+1-6+8y³+12y²+6y+6y` `=(x³-9x²+27x-27)+(8y³+12y²+6y+1)+(3x+6y-6)` `=(x³-3.x².3+3.x.3²-3³)+[(2y)³+3.(2y)².1+3.2y.1²+1³]+3(x+2y-2)` `=(x-3)³+(2y+1)³+3(x+2y-2)` Vế phải bằng vế trái đẳng thức được chứng minh Reply
`#DyHungg`
`x³-9x²+30x-20+8y³+12y²+12y-12`
`=(x³-9x²+27x-27)+(8y³+12y²+6y+1)+(3x+6y-6)`
`=(x-3)³+(2y+1)³+3(x+2y-2)`
`⇒đpcm`
`VP=x³-9x²+30x-20+8y³+12y²+12y-12`
`=x³-9x²+30x-32+8y³+12y²+12y`
`=x³-9x²+27x+3x-27+1-6+8y³+12y²+6y+6y`
`=(x³-9x²+27x-27)+(8y³+12y²+6y+1)+(3x+6y-6)`
`=(x³-3.x².3+3.x.3²-3³)+[(2y)³+3.(2y)².1+3.2y.1²+1³]+3(x+2y-2)`
`=(x-3)³+(2y+1)³+3(x+2y-2)`
Vế phải bằng vế trái đẳng thức được chứng minh