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31. Let
be defined
as in Problem 30 above and show:
(a)
if
f(x) is a polynomial of degree less than n.
(b)
if
f(x) = a0xn + a1xn
-1 + ... + an.
32. Let f(x) = a + bx + cx2. Let r = f(0), s = f(1) - f(0), and t = f(2) - 2f(1) + f(0).
(a) Show that f(x) = r + sx + tx(x - 1)/2.
(b) Generalize this problem.
33. Let f(x) = 5x4 - 6x3
- 3x2 + 8x + 2. Use repeated synthetic division
to find numbers a, b, c, d, and e such that
34. Use the method of the alternate solution for Example
3 in Section 8.1 to do Problem 33.
35. Let f(x) = x3 + ax2
+ bx + c, and let a, b, c, and r be complex
numbers. Show that
and express s in terms of a and r.
36. Let f(x) = x3 + ax2
+ bx + c, and let r be a root of f(x)
= 0. Show that f(x) is divisible by
(x - r)2 if and only if 3r2 + 2ar
+ b = 0. [If m is an integer greater than 1 and a polynomial
f(x) is divisible by (x - r)m
but not by (x - r)m+1, we say that r
is a multiple root of f(x) = 0 with multiplicity
m.]
37. Let f(x) = x3 + ax2
+ bx + c, g(x) = 3x2 + 2ax
+ b, and h(x) = 6x + 2a. Show that
f(x) = (x - r)3 if and only if f(r)
= g(r) = h(r) = 0.
38. Let f(x) = x4 + ax3
+ bx2 + cx + d. Find s, t, and u
in terms of a, b, c, and r such that
39. Do the methods of this chapter enable you to solve x3
- 3x + 1 = 0?
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