28. Show that

(a) 

(b) 

(c) 

29. Show that 

30. Show that 

31. Expand (x + y + z)⁴ by expanding (w + z)⁴, then replacing w by x + y, and expanding further.

32. Expand (x + y - z)⁴.

33. The sum of squares  is expressible in the form  Find m.

34. Express each of the following in the form 

(a) 

(b) 

(c) 
 

35. Use (x³ + 3x² +3x + 1)² = [(x + 1)³]² = (x + 1)⁶ to show the following:

(a) 

(b) 

(c) 

(d)