Rút gọn
A=(x+3)(x^2-3x+9)-(54+x^3)
B=(2x+y)(4x^2-2xy+y^2)-(2x-y)(4x^2+2xy+y^2)
C=(a+b)^2-(a-b)^2
D=(a+b)^3-(a-b)^3-2b^3
E=(x+y+z)-2(x+y+z)(x+y)+(x+y)^2
Rút gọn
A=(x+3)(x^2-3x+9)-(54+x^3)
B=(2x+y)(4x^2-2xy+y^2)-(2x-y)(4x^2+2xy+y^2)
C=(a+b)^2-(a-b)^2
D=(a+b)^3-(a-b)^3-2b^3
E=(x+y+z)-2(x+y+z)(x+y)+(x+y)^2
`A = (x + 3)(x^2 – 3x + 9) – (54 + x^3)`
`A = x^3 + 27 – 54 – x^3`
`A = -27`
`B = (2x + y)(4x^2 – 2xy + y^2) – (2x – y)(4x^2 + 2xy + y^2)`
`B = 8x^3 + y^3 – 8x^3 + y^3`
`B = 2y^3`
`C = (a + b)^2 – (a – b)^2`
`C = (a + b – a + b)(a + b + a – b)`
`C = 2b.2a`
`C = 4ab`
`D = (a + b)^3 – (a – b)^3 – 2b^3`
`D = (a + b – a + b)[(a + b)^2 + (a + b)(a – b) + (a – b)^2] – 2b^3`
`D = 2b . (a^2 + 2ab + b^2 + a^2 – b^2 + a^2 – 2ab + b^2) – 2b^3`
`D = 2b . (3a^2 + b^2) – 2b^3`
`D = 6a^2b + 2b^3 – 2b^3`
`D = 6a^2b`
`E = (x + y + z)^2 – 2(x + y + z)(x + y) + (x + y)^2`
`E = (x + y + z – x – y)^2`
`E = z^2`
$\text{câu E hình như thiếu mũ 2 thì phải :v nếu k có mũ hai thì lẻ lắm :3}$
`A=(x+3)(x^2-3x+9)-(54+x^3)`
`A=x^3+27-54-x^3`
`A=(x^3-x^3)+27-54`
`A=0-27=-27.`
`B=(2x+y)(4x^2-2xy+y^2)-(2x-y)(4x^2+2xy+y^2)`
`B=8x^3+y^3-(8x^2-y^3)`
`B=8x^3+y^3-8x^3+y^3`
`B= (8x^3-8x^3)+(y^3+y^3)`
`B= 2y^3.`
`C=(a+b)^2-(a-b)^2`
`C=a^2+2ab+b^2-(a^2-2ab+b^2)`
`C=a^2+2ab+b^2-a^2+2ab-b^2`
`C=(a^2-a^2)+(b^2-b^2)+(2ab+2ab)`
`C=4ab.`
`D=(a+b)^3-(a-b)^3-2b^3`
`D=a^3+3a^2b+3ab^2+b^3-(a^3-3a^2b+3ab^2-b^3)-2b^3`
`D=a^3+3a^2b+3ab^2+b^3-a^3+3a^2b-3ab^2+b^3-2b^3`
`D=(a^2-a^2)+3a^2b+3a^2b+3ab^2-3ab^2+(b^3+b^3-2b^3)`
`D=6a^2b.`
`E=(x+y+z)^2-2(x+y+z)(x+y)+(x+y)^2`
`E=(x+y+z-x-y)^2`
`E=z^2.`
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