~ Bạn tham khảo ~
`a,` Ta có :
`H(x) = x^4 + 2x^2 + 1`
`= (x^2)^2 + 2x^2 .1 + 1^2`
`= (x^2 + 1)^2`
`=> H(0) = (0^2 + 1)^2 = 1^2 = 1`
`=> H(-1) = [(-1)^2 + 1]^2 = 2^2 = 4`
`=> H(-1/2) = [(-1/2)^2 + 1]^2 = (5/4)^2 = 25/16`
`b,` Ta có :
`K(y) = y^4 + 4y^3 + 2y^2 - 4y + 1`
`= y^4 + 2y^3 - y^2 + 2y^3 + 4y^2 - 2y - y^2 - 2y + 1`
`= y^2 (y^2 + 2y - 1) + 2y(y^2 + 2y - 1) - (y^2 + 2y - 1)`
`= (y^2 + 2y -1)(y^2 + 2y -1)`
`= (y^2 + 2y - 1)^2`
`=> K(-2) = [(-2)^2 + 2.(-2) - 1]^2 = (-1)^2 = 1`
`=> K(1) = (1^2 + 2.1 - 1)^2 = 2^2 = 4`
`=> K(1/3) = [(1/3)^2 + 2. 1/3 - 1]^2 = (-1/6)^2 = 1/36`
