Answer:
The distance is 36 miles.
Step-by-step explanation:
distance in either direction = d
total time = 5
time going = t
time returning = 5 - t
speed = distance/time
going:
speed = distance/time
18 = d/t
d = 18t Eq. 1
returning:
speed = distance/time
12 = d/(5 - t)
60 - 12t = d
d = 60 - 12t Eq. 2
Eq. 1 and Eq. 2 form a system of equations.
d = 18t
d = 60 - 12t
Since d = d, then 18t must equal 60 - 12t
18t = 60 - 12t
30t = 60
t = 2
d = 18t = 18(2) = 36
The distance is 36 miles.
Answer:
32, 47, x+17, 43
Step-by-step explanation:
just add or subtract by 17
When trying to solve a system of equations graphically, our focus is on identifying the coordinates of any point through which the graphs go. Look at the above graph: you'll see that the red and the blue graphs intersect at (0,2), and so (0,2) is a "solution" of that system of equations.
Here, we're asked to answer a different kind of question: "Is (2,0) a solution to the given system of equations?" Let's paraphrase that question: "Do both graphs go through (2,0)?" The answer: emphatically not. Neither graph goes through (2,0). Thus, (2,0) is not a solution to this system of equations.
Let us model this problem with a polynomial function.
Let x = day number (1,2,3,4, ...)
Let y = number of creatures colled on day x.
Because we have 5 data points, we shall use a 4th order polynomial of the form
y = a₁x⁴ + a₂x³ + a₃x² + a₄x + a₅
Substitute x=1,2, ..., 5 into y(x) to obtain the matrix equation
| 1 1 1 1 1 | | a₁ | | 42 |
| 2⁴ 2³ 2² 2¹ 2⁰ | | a₂ | | 26 |
| 3⁴ 3³ 3² 3¹ 3⁰ | | a₃ | = | 61 |
| 4⁴ 4³ 4² 4¹ 4⁰ | | a₄ | | 65 |
| 5⁴ 5³ 5² 5¹ 5⁰ | | a₅ | | 56 |
When this matrix equation is solved in the calculator, we obtain
a₁ = 4.1667
a₂ = -55.3333
a₃ = 253.3333
a₄ = -451.1667
a₅ = 291.0000
Test the solution.
y(1) = 42
y(2) = 26
y(3) = 61
y(4) = 65
y(5) = 56
The average for 5 days is (42+26+61+65+56)/5 = 50.
If Kathy collected 53 creatures instead of 56 on day 5, the average becomes
(42+26+61+65+53)/5 = 49.4.
Now predict values for days 5,7,8.
y(6) = 152
y(7) = 571
y(8) = 1631
