Problem Set 4 - Using Factoring to Solve Equations | MATH 1300, Assignments of Elementary Mathematics

Material Type: Assignment; Class: Fundamentals of Math; Subject: (Mathematics); University: University of Houston; Term: Unknown 2004;

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Pre 2010

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Exercise Set 4.4: Using Factoring to Solve Equations
Math 1300, Fundamentals of Mathematics
The University of Houston Chapter 4: Factoring
Solve the following equations by factoring.
1. 02110
2=+ xx
2. 04013
2=++ xx
3. 0128
2=++ xx
4. 0406
2= xx
5. 35)2( =xx
6. 20)8( =+xx
7. 7214
2=+ xx
8. xx 1160
2=
9. 01572 2= xx
10. 0473 2=+ xx
11. 12176 2=+ xx
12. 6710 2= xx
13. 253 2= xx
14. 0568 2= xx
15. 025
2=x
16. 049
2=x
17. 094 2=x
18. 02536 2=x
Solve the following equations by factoring. To simplify
the process, remember to first factor out the Greatest
Common Factor (GCF) and to factor out a negative if
the leading coefficient is negative.
19. 08
2= xx
20. 010
2=+ xx
21. 25360xx−− + =
22. 214 48 0xx−− =
23. 0213 2=+ xx
24. 0305 2= xx
25. 0123 2=x
26. 077 2=+ x
27. 090155 2=+ xx
28. 024204 2=++ xx
29. 03023080 2=+ xx
30. 0187512 2=+ xx
31. 32
560xxx
+
+=
32. 32
7180xx x
−=
Each of the quadratic functions below is written in the
form 2
()fx ax bx c
=
++
. The graph of a quadratic
function is a parabola with vertex, where 2
b
a
h=
and
(
)
2
b
a
kf=.
(a) Find the x-intercept(s) of the parabola by
setting () 0fx
=
and solving for x.
(b) Write the coordinates of the x-intercept(s)
found in part (a).
(c) Find the y-intercept of the parabola and write
its coordinates.
(d) Give the coordinates of the vertex (h, k) of the
parabola, using the formulas 2
b
a
h=
and
(
)
2
b
a
kf=.
(e) Does the parabola open upward (with the
vertex being the lowest point on the graph) or
downward (with the vertex being the highest
point on the graph)?
(f) Find the axis of symmetry. (Be sure to write
your answer as an equation of a line.)
(g) Draw a graph of the parabola that includes
the features from parts (b) through (e).
33. 2
() 6 8fx x x
=
−+
34. 2
() 2 15fx x x
=
−−
35. 2
() 8 16fx x x
=
−+
36. 2
( ) 10 16fx x x
−+
37. 2
() 4 21fx x x
=
−− +
38. 2
() 10 25fx x x
=
++
39. 2
() 3 12 36fx x x
+−
40. 2
() 4 8 5fx x x
=
−−+
pf2

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Exercise Set 4.4: Using Factoring to Solve Equations

Math 1300, Fundamentals of Mathematics The University of Houston Chapter 4: Factoring

Solve the following equations by factoring.

1. x^2 − 10 x + 21 = 0 2. x^2 + 13 x + 40 = 0 3. x^2 + 8 x + 12 = 0 4. x^2 −^6 x −^40 =^0 5. x ( x − 2 )= 35 6. x ( x + 8 )= 20 7. x^2 + 14 x = 72 8. x^2 − 60 = 11 x 9. 2 x^2 − 7 x − 15 = 0 10. 3 x^2 − 7 x + 4 = 0 11. 6 x^2 + 17 x =− 12 12. 10 x^2 − 7 x = 6 13. 3 x^2 − 5 x =− 2 14. 8 x^2 − 6 x − 5 = 0 15. x^2 − 25 = 0 16. x^2 −^49 =^0 17. 4 x^2 − 9 = 0 18. 36 x^2 − 25 = 0

Solve the following equations by factoring. To simplify the process, remember to first factor out the Greatest Common Factor (GCF) and to factor out a negative if the leading coefficient is negative.

19. x^2 − 8 x = 0 20. x^2 + 10 x = 0 21.x^2^ − 5 x + 36 = 0 22.x^2^ − 14 x − 48 = 0 23. − 3 x^2 + 21 x = 0 24. 5 x^2 − 30 x = 0 25. 3 x^2 − 12 = 0 26. − 7 x^2 + 7 = 0 27. − 5 x^2 − 15 x + 90 = 0 28. − 4 x^2 + 20 x + 24 = 0 29. 80 x^2 + 230 x − 30 = 0 30. 12 x^2 − 75 x + 18 = 0 31. x^3^ + 5 x^2 + 6 x = 0 32. x^3^ − 7 x^2 − 18 x = 0

Each of the quadratic functions below is written in the form f^ (^ x^ ) =^ ax^^2 +^ bx^ +^ c****. The graph of a quadratic

function is a parabola with vertex, where h = − 2^ ba

and k = f ( − 2^ ba ).

(a) Find the x -intercept(s) of the parabola by setting f ( x ) = 0 and solving for x****. (b) Write the coordinates of the x- intercept(s) found in part (a). (c) Find the y- intercept of the parabola and write its coordinates. (d) Give the coordinates of the vertex ( h , k ) of the

parabola, using the formulas h = − 2^ ba and

b

k = f − a.

(e) Does the parabola open upward (with the vertex being the lowest point on the graph) or downward (with the vertex being the highest point on the graph)? (f) Find the axis of symmetry. (Be sure to write your answer as an equation of a line.) (g) Draw a graph of the parabola that includes the features from parts (b) through (e).

33. f ( ) x = x^2 − 6 x + 8 34. f ( ) x = x^2 − 2 x − 15 35. f ( ) x = x^2 − 8 x + 16 36. f ( ) x = − x^2 + 10 x − 16 37. f ( ) x = − x^2 − 4 x + 21 38. f ( ) x = x^2 + 10 x + 25 39. f ( ) x = 3 x^2 + 12 x − 36 40. f ( ) x = − 4 x^2 − 8 x + 5

Exercise Set 4.4: Using Factoring to Solve Equations

Math 1300, Fundamentals of Mathematics The University of Houston Chapter 4: Factoring

41. f ( ) x = x^2 − 16 42. f ( ) x = 25 − x^2 43. f ( ) x = 9 − 4 x^2 44. f ( ) x = 9 x^2 − 100

Find the x- intercept(s) of the following.

45. f ( ) x = x^3 + 7 x^2 + 10 x 46. f ( ) x = x^3 − 2 x^2 − 99 x 47. f ( ) x = x^3 − 25 x 48. f ( ) x = x^3 − 4 x 49. f^ ( ) x^^ =^ x^^3 −^2 x^2^ −^9 x +^18 50. f ( ) x = x^3 + 4 x^2 − x − 4

For each of the following problems: (a) Model the situation by writing appropriate equation(s). (b) Solve the equation(s) and then answer the question posed in the problem.

51. The length of a rectangular frame is 5 cm longer than its width. If the area of the frame is 36 cm^2 , find the length and width of the frame. 52. The width of a rectangular garden is 8 m shorter than its length. If the area of the field is 180 m^2 , find the length and the width of the garden 53. The height of a triangle is 3 cm shorter than its base. If the area of the triangle is 90 cm^2 , find the base and height of the triangle. 54. Find x if the area of the figure below is 26cm^2. (Note that the figure may not be drawn to scale.)

x cm

x cm

3 cm

8 cm