15. What is the degree of the expression 5x2 + 7x - X"? A. 2 B. 3 0.7 c.a -n 16. What must be the value of n so that the term xi-n is of degree 2? A. - 2 B.- 1 D. 1 C.O 17. In the quadratic function of the form y = ax2 + bx + c, which of the following must not be equal to 0? D. X-term A. a B. b c.c 18. Which of the following is a quadratic function? A. y = 5x - 4 C. y = 2x2 - 5x2 D.y = 21 - X-8 B. y = x - 3x2 19. Express f(x) = 3(x – 7)2 + 5, in the form f(x) = ax? + bx + c ? A. f(x) = 3x2 - 21x + 152 C. f(x) = 3x2 – 212 + 54 B. f(x) = 3.x2 - 42x + 152 D. f(x) = 3x2 - 42x + 54 D. XA-1 = 2x = - 20. Which of the following is in the second degree equation? A. 7x3 - 5x = 4 B. 2* - 3 = 16 C. 5x – 2x2 = 0