1) (x + 1) D 10. Which of the following is TURE about the equation x(x + 7) = -10? a. The equation is not quadratic. b. The equation is quadratic since multiplying the left side of the equation results to x². c. The equation is not quadratic since although x2 will be obtained, the right side of the equation is still negative. d. The equation is quadratic and is already in standard form.​