`b)`
`(x+1)(x^2 - x +1) +(x+1) (x-1)`
` = (x+1)[ (x^2 - x+1) + (x-1)]`
` = (x+1)(x^2 - x + 1 + x-1)`
` = x^2 (x+1)`
` =x^3 + x^2`
`c)`
`(2y^3 + 4y^2 + 5y + 3) : (y+1)`
` = (2y^3 + 2y^2 + 2y^2 + 2y + 3y + 3) : (y+1)`
` = [2y^2 (y+1) + 2y (y+1) + 3(y+1)] : (y+1)`
` = (2y^2 + 2y + 3)(y+1) : (y+1)`
` = 2y^2 + 2y + 3`
`d)`
`(6a^3 + a^2 - 29a + 21) : (2a-3)`
` = (6a^3 - 9a^2 + 10a^2 - 15a - 14a + 21) : (2a-3)`
` = [3a^2 (2a-3) + 5a (2a - 3) - 7 (2a-3)] : (2a-3)`
` = (3a^2 + 5a- 7)(2a-3) : (2a-3)`
` = 3a^2 + 5a - 7`
