Answer:
8
Step-by-step explanation:
Table:
x y
-3 0.5
-2 1
-1 2.5
0 5
1 8.5
Now, y = ax^2 + bx + c
Start replacing x = 0 and y = 5
5 = a(0) + b(0) + c => c = 5.
Now, replace any other two pair of data:
(-2, 1) => -1 = a(-2)^2 + b(-2)
-1 = 4a - 2b
(1, 8.5) => 8.5 = a(1)^2 + b(1)
8.5 = a + b
Solve the system
4a - 2b = - 1
a + b = 8.5
=>
4a - 2b = - 1
2a + 2b = 17
-------------------------
6a = 16
=> a = 16 / 6 = 8/3
b = 8.5 - a = 17/2 - 8/3 = 35/6
=> y = (8/3)x^2 + (35/6)x + 5 <--------- answer
Answer: the speed of the plane is 130 mph
Step-by-step explanation:
Let x represent the speed of the plane. If the car travels 80 mph slower than the plane, then the speed of the car would be (x - 80) mph.
Time = Distance/speed
plane can fly 520 miles in the same time as it takes a car to go 200 miles. This means that the time it takes the plane to fly 520 miles is
520/x
Also, the time it takes the car to drive 200 miles is
200/(x - 80)
Since the time is the same, it means that
520/x = 200/(x - 80)
Cross multiplying, it becomes
520(x - 80) = 200 × x
520x - 41600 = 200x
520x - 200x = 41600
320x = 41600
x = 41600/320
x = 130 mph
