The document discusses the relationships between the roots and coefficients of polynomial equations. It provides formulas to find the sum of roots taken one, two, three, or more at a time in terms of the coefficients. For a polynomial of degree n in the form ax^n + bx^(n-1) + cx^(n-2) + ..., the formulas are provided to find the sum of roots one at a time as -b/a, two at a time as c/a, three at a time as -d/a, and so on. An example is also given to demonstrate using the formulas.
5. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
6. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b
a
7. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
8. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
9. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
Quartics ax 4 bx 3 cx 2 dx e 0
10. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
Quartics ax 4 bx 3 cx 2 dx e 0
b
a
11. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
Quartics ax 4 bx 3 cx 2 dx e 0
b c
a a
12. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
Quartics ax 4 bx 3 cx 2 dx e 0
b c
a a
d
a
13. Roots and Coefficients
Quadratics ax 2 bx c 0
b c
a a
Cubics ax 3 bx 2 cx d 0
b c
a a
d
a
Quartics ax 4 bx 3 cx 2 dx e 0
b c
a a
d e
a a
15. For the polynomial equation;
ax n bx n1 cx n2 dx n3 0
b
a (sum of roots, one at a time)
16. For the polynomial equation;
ax n bx n1 cx n2 dx n3 0
b
a (sum of roots, one at a time)
c
a (sum of roots, two at a time)
17. For the polynomial equation;
ax n bx n1 cx n2 dx n3 0
b
a (sum of roots, one at a time)
c
a (sum of roots, two at a time)
d
a (sum of roots, three at a time)
18. For the polynomial equation;
ax n bx n1 cx n2 dx n3 0
b
a
(sum of roots, one at a time)
c
a
(sum of roots, two at a time)
d
a
(sum of roots, three at a time)
e
a
(sum of roots, four at a time)
19. For the polynomial equation;
ax n bx n1 cx n2 dx n3 0
b
a
(sum of roots, one at a time)
c
a
(sum of roots, two at a time)
d
a
(sum of roots, three at a time)
e
a
(sum of roots, four at a time)
Note:
2
2 2
20. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
21. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5
2
22. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3
2 2
23. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
24. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
25. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
26. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b)
27. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b)
28. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b)
3
2
1
2
29. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b)
3
2
1
2
3
30. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b) c) 2 2 2
3
2
1
2
3
31. e.g. (i ) If , and are the roots of 2 x 3 5 x 2 3 x 1 0, find the
values of;
a) 4 4 4 7
5 3 1
2 2 2
5 1
4 4 4 7 4 7
2 2
27
2
1 1 1
b) c) 2 2 2
2
2
3
2
1
2
3
34. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
35. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
36. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
37. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
1
38. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
1
1 1 1
(iii)
39. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
1
1 1 1
(iii)
1 1 1
40. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
1
1 1 1
(iii)
1 1 1
3
1
41. 1988 Extension 1 HSC Q2c)
If , and are the roots of x 3 x 1 0 find:
3
(i)
0
(ii)
1
1 1 1
(iii)
1 1 1
3
1
3
42. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
43. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
44. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
2
45. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
2
3
46. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
P 3 0
2
3
47. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
P 3 0
2
3 2 3 3 k 3 6 0
3 2
48. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
P 3 0
2
3 2 3 3 k 3 6 0
3 2
54 9 3k 6 0
49. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
P 3 0
2
3 2 3 3 k 3 6 0
3 2
54 9 3k 6 0
3k 39
50. 2003 Extension 1 HSC Q4c)
It is known that two of the roots of the equation 2 x 3 x 2 kx 6 0 are
reciprocals of each other.
Find the value of k.
1
Let the roots be , and
1 6
P 3 0
2
3 2 3 3 k 3 6 0
3 2
54 9 3k 6 0
3k 39
k 13
51. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
52. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
53. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
54. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
55. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
1 1 s
56. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
1 1 s
s 2
57. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
1 1 s 1 t
s 2
58. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
1 1 s 1 t
s 2 t 2
59. 2006 Extension 1 HSC Q4a)
The cubic polynomial P x x 3 rx 2 sx t , where r, s and t are real
numbers, has three real zeros, 1, and
(i) Find the value of r
1 r
r 1
(ii) Find the value of s + t
1 1 s 1 t
s 2 t 2
s t 0