25. For all real numbers a, b, c, x, y, and z show that

26. For all real numbers a₁, a₂, ..., a_n, b₁, b₂, ..., b_n, show that

27. Show that if a and b are positive real numbers and m and n are positive integers, then

28. Let F_n and L_n be the nth Fibonacci and nth Lucas number, respectively. Prove that

for all integers 
 
 

Monday, June 22, 1998