Đáp án + Giải thích các bước giải:
` a) ( 2x+3 )³ = 8x³ + 36x² + 54x + 27 `
` b) ( 2x+5y )³ = 8x³ + 60x²y + 150xy² + 125y³ `
` c) ( 4x-3y )³ = 64x³ - 144x²y + 108xy² - 27y³ `
` d) ( 3y-5x )³ = 27y³ - 135y²x + 225yx² - 125x³ `
` e) ` ($\dfrac{1}{4}x$ + $\dfrac{4}{3}y$)³ = $\dfrac{1}{64}x³$ + $\dfrac{1}{12}x²y$ + $\dfrac{4}{9}xy²$ + $\dfrac{64}{27}y³$
` f) `($\dfrac{5}{4}y$ - $\dfrac{1}{5}x$)³ = $\dfrac{125}{64}y³$ - $\dfrac{15}{16}y²x$ + $\dfrac{1}{20}yx²$ + $\dfrac{1}{125}x³$
` g) x³ + 3³ = ( x+3 )( x² - 3x + 9 ) `
` h) x³ - y³ = ( x-y )( x²+ xy+y²)`
` i) x³+8 = (x+2)(x²-2x+4)`
` j) 1000-y³ = (10-y)(100+10y+y²)`
` k) 125-8x³ = (5-2x)(25+10x+4x²)`
` l) x³ + 27y³ = ( x+3x)(x²-3xy+9y²)`
` HĐT: ( a + b )³ = a³ + 3a²b + 3ab²+ b³`
` ( a - b )³ = a³ - 3a²b + 3ab² - b³ `
` a³ + b³ = ( a + b ) ( a² - ab + b² )`
` a³ - b³ = ( a - b ) ( a² + ab + b² )`
