Download MATH 120 chapter 3 online quiz

MATH 120 chapter 3 online quiz
1. When using elimination, which would be an acceptable first step to solve the
following system.
x-y=6
x + 2y = 6
a) Multiply the top equation by 2. *
b) Multiply the top equation by -2 .
c) Add the two equations together.
d) Solve the top equation for x by adding y to each side.
2. When using substitution, which would be an acceptable first step to solve the
following system.
2y - 5x = 2
x-y=4
a) Multiply the bottom equation by 2.
b) Multiply the bottom equation by -5.
c) Add the two equations together.
d) Add y to both sides in the bottom equation to get x alone.*
3. What best describes the solution to the system?
-x - 2y = -3
2x + 4y = 6
a) There is no solution.
b) (0,0)
c) There are an infinite number of solutions. *
d) (-1,2)
4. What best describes the solution to the system 5x-y=10 and 5x-y=12
a) There is no solution. *
b) (0,0)
c) There are an infinite number of solutions.
d) (-1,2)
5. Which of the following systems of equations could be used to solve the
following: The perimeter of a rectangle is 94. The length is three more than the
width. Find the length and the width.
a)
b)
c)
d)
l + w = 94 and l = 3 + w
2l + 2w = 94 and l = 3 + w *
lw = 94 and w = l - 3
2w = 2l + 3 and 2w + 2l = 94
6. Which of the following systems of equations could be used to solve the
following: Two cars leave from Chicago heading in opposite directions. The
first car travels at 60 m.p.h. while the second travels at 70 m.p.h. In how many
hours will they be 600 miles apart?
a) d - 600 = 60t and d+600 =70t
b) d = 60 t + 70 and d=600 - 70t
c) d =60t and 600 - d = 70t *
d) d = t +10 and 10d =60
7. Which of the following systems could be used to solve the following: A
motorboat traveled upstream for 3 hours against an 8 m.p.h current. The trip
downstream with the same current took 2 hours. How fast could the canoe go
in still water?
a) d=2(r+8) and d=3(r-8) *
b) d=3(r+8) and d=2(r-8)
c) d=2r+8 and d=3r-8
d) d=2r+8 and d=3r-8
8. Which of the following systems could be used to solve the following: A
medication that is 20% alcohol is combined with a similar medication that is
38% alcohol. How many liters of each should be combined to make 40 liters of
a medication that is 25% alcohol?
a) .2x+.38y=40 and x+y=10
b) .2x+.38y=.25 and x+y=10
c) .2x+.38y=10 and x+y=40 *
d) .2x+.38y=10 and x+y=40
9. Find the solution to the following system:
2x+y+2z=3
x+6y+3z=4
3x-2y+z=0
a)
b)
c)
d)
(1,1,-1)
(2,-1,4)
(-2,-1,-4)
(-2,-1,4) *
10. Which of the following systems of equations could be used to solve the
following: The sum of three numbers is 25. The first number added to three
times the second is five less than the third. The first number is 4 more than
three times the second.
a) x+y+z=25 and x=3+2y-5z and x=4+3y
b) x+y+z=25 and x+3=2y-5z and x=4+3y
c) x+y+z=25 and x+3y=z-5 and x=4+3y *
d) x+y+z=25 and x+3y=5-z and x=4+3y