# Algebra

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I have a few questions I need help with. They are to help review for our exam.

4) Without graphing, is each system independent, dependent, or inconsistent?
-x-3y=0
x-y=4
(i believe dependent)
dependent
independent
inconsistent

6) Which matrix represents the system of equations below?
-2x-7y=3
7x-6y=12
(not sure)
-2 -7 3
7 -6 12

-2 -7 -3
7 -6 12

7 -6 12
-2 -7 3

-2 -7 -3
7 -6 12

7) Which steps translate the graph of y=x^2 to y=-(x-3)^3+2
(my choice translate 3 unite to right translate up 2 units)

translate 3 units to the right, translate up 2 units

reflect across the x-axis, translate 3 units to the left, translate down 2 units

translate 3 units to the left, translate down 2 units

reflect across the x-axis, translate 3 units to the right, translate up 2 units

15) The half-life of a certain radioactive material is 68 hours. An initial amount of the material has a mass of 641kg. Write an exponential function that models the decay of this material. Find how much radioactive material remains after 4 hours. Round your answer to the nearest thousandth.

y=641(1/2)^68x;0kg

y=1/2(1/641)^1/68x;0.342kg

y=641(1/2)^1/68x;615.390kg

y=2(1/641)^1/68x;1.367kg

18) Name the property of real numbers illustrated by the equation

5*(sqrt 9*4)=(5*sqrt9)*4
(my choice commutative property of multiplication)

commutative property of multiplication
associative property of multiplication
distributive property

20) The table shows the median home prices in Florida. What is the equation of a trend line that models a relationship between time and home prices? Use the equation to predict the median home price in 2020.

year 1940 1950 1960 1970 1980 2000
median price(\$) 20,600 38,300 54,000 60,500 85,300 100,300 111,100
(my choice y=1508.33x+20,600;\$141,300)

y=45.25x+20,600;111,100
y=1508.33x+20,600;141,300
y=1508.33+20,600;111,100
y=45.25x+20,600;141,300

I know this may seem like alot but it is review, so if someone might beable to help me out so I can be ready to take exam. Thank you in advance

• Algebra - ,

independent
dependent if the lines are parallel

6)
look at the coefficients!
1st set matches

7)
reflect across the x-axis, translate 3 units to the right, translate up 2 units

15)
think about it: every 68 hours it divides in half. So, the exponential will be (1/2)^(x/68)

y=641(1/2)^1/68x;615.390kg

18)
associative
You have a*(b*c) = (a*b)*c

commutative would be a*(b*c) = a*(c*b) or (b*c)*a

20)
If x represents the years since 1940, then I agree.

• Algebra - ,

Thank you Steve this helps alot studying for exam