Đáp án+Giải thích các bước giải:
`a) 5/6x²y + 7/12xy² + 11/18xy `
`=(30y +21x+22xy )/(36x²y²)`
`b) (4x+2)/(15x³y) + (5y-3)/(9x²y) + (x+1)/(5xy³)`
`= ( 3y²(4x+2) + 5xy² (5y-3) + 9x³(x+1) )/ (45x³y³)`
`= (12xy² + 6y² + 25xy³ - 15xy² + 9x^4 + 9x^3)/(45x³y³)`
`= (25xy^3 - 3xy^2 + 6y^2 + 9x^4 + 9x^3)/(45x³y³)`
`c) 3/(2x )+(3x-3)/(2x-1)+(2x²+1)/(4x²-2x)`
`= 3/(2x )+(3x-3)/(2x-1) + (2x²+1)/(2x(2x-1))`
`= (3(2x-1)+2x(3x-3) + 2x² +1) / (2x(2x-1))`
`= (6x-3+6x²-6x+2x²+1)/(2x(2x-1))`
`=(8x²-2)/(2x(2x-1))`
`=(2(4x²-1))/(2x(2x-1))`
`=((2x-1)(2x+1))/(x(2x-1))`
`=(2x+1)/x`
`d) (x³ + 2x)/(x³+1) + (2x)/(x³-x+1) + 1/(x+1)`
`= (x²+2x + 2x(x+1) + x³ - x +1)/(x³+1)`
`= (x²+2x+2x²+2x+x³-x+1)/(x³+1)`
`= (x³+3x²+3x+1)/(x³+1)`
`=((x+1)³)/(x³+1)`
