greenlollipop3 greenlollipop3 21-11-2018 Mathematics contestada combine like terms to simplify the expression: 7x + 3y - 2 + 6x + 1 + y^2a. 2y^3 + 13x - 1b. y^2 + 3y + 13x - 1c. y^2 + 3y + 13x^2 + 1d. 3y^3 + 13x^2 + 1