Step-by-step explanation:
so, it is a quadratic equation :
-3x² + 30x - 90 = 0
the first thing we can do is divide by 3
-x² + 10x - 30 = 0
remember, the formula to solve and find the 2 solutions is
x = (-b ± sqrt(b² - 4ac))/(2a)
in our case here
a = -1
b = 10
c = -30
x = (-10 ± sqrt(100 - 4×-1×-30))/-2 =
= (-10 ± sqrt(100 - 120))/-2 = (-10 ± sqrt(-20))/-2 =
= (-10 ± sqrt(4×5)i)/-2 = (-10 ± 2×sqrt(5)i)/-2 =
= 5 ± -sqrt(5)i
x1 = 5 - sqrt(5)i
x2 = 5 + sqrt(5)i
remember, i = sqrt(-1), a complex number.
Answer:
x=-10 and y=1
Step-by-step explanation:
-2(-10)=20
-10(1)=-10
20-10=10
Answer:
a)
b) r =-0.932
The % of variation is given by the determination coefficient given by
and on this case
, so then the % of variation explained by the linear model is 86.87%.
Step-by-step explanation:
Assuming the following dataset:
Monthly Sales (Y) Interest Rate (X)
22 9.2
20 7.6
10 10.4
45 5.3
Part a
And we want a linear model on this way y=mx+b, where m represent the slope and b the intercept. In order to find the slope we have this formula:
Where:
With these we can find the sums:
And the slope would be:
Nowe we can find the means for x and y like this:
And we can find the intercept using this:
So the line would be given by:
Part b
For this case we need to calculate the correlation coefficient given by:
So then the correlation coefficient would be r =-0.932
The % of variation is given by the determination coefficient given by
and on this case
, so then the % of variation explained by the linear model is 86.87%.
The answer is A: S11=(11Ek=11)6+(k-1)2