(BRAINLIST!!!)70 POINTS!!! ASAP Write two different expressions equivalent to 8d - 4) Use factoring for one way
1 answer:
You might be interested in
The rate of decrease in the revenue reduces each year, resulting in an
approximate quadratic equation model that is concave upwards.
The difference between the actual and predicted values are;
Reasons:
The variables are;
x = Number of years since 2,000
y = Revenue for physically recorded music in millions of dollars
Required:
To model the decline using a quadratic equation.
Solution:
The general form of the quadratic equation is; y = a·x² + b·x + c
When y = 5547, x = 8
We get;
5547 = a·8² + b·8 + c = 64·a + 8·b + c
5547 = 64·a + 8·b + c...(1)
When y = 3113, x = 11
We get;
3113 = a·11² + b·11 + c = 121·a + 11·b + c
3113 = 121·a + 11·b + c...(2)
When y = 2056, x = 14
We get;
2056 = a·14² + b·14 + c = 196·a + 14·b + c
2056 = 196·a + 14·b + c...(3)
Subtracting equation (2) from equation (1) gives;
5547 - 3113 = 64·a + 8·b + c - (121·a + 11·b + c) = -57·a - 3·b
2434 = -57·a - 3·b...(4)
Subtracting equation (3) from equation (2) gives;
3113 - 2056 = 121·a + 11·b + c - (196·a + 14·b + c) = -75·a - 3·b
1057 = -75·a - 3·b...(5)
Subtracting equation (5) from equation (4) gives;
2434 - 1057 = -57·a - 3·b - (-75·a - 3·b) = 18·a
1377 = 18·a
a = 76.5
From, equation (4), 2434 = -57·a - 3·b, we have;
2434 = -57 × 76.5 - 3·b
Therefore;
b = -2264.8
From equation (1), we get;
5547 = 64 × 76.5 + 8×(-2264.8) + c
Therefore;
c = 5547 - (64 × 76.5 + 8×(-2264.8)) = 18769.
c = 18769.
Therefore, the quadratic model is;
Verifying, we have in year 2012, x = 12
y = 76.5×12² - 2264.8×12 + 18769.
= 2607.74
The completed table and comparison of the predicted physical revenue
and actual values is presented as follows;
Learn more here:
