Answer:
Step-by-step explanation:
To solve using completing square, we need to write the equation as x2+3x=17.
The next step is to add a number such that the square can be completed. The number must be equal to (b/2a)^2, so here it will be (3/2)^2 = 9/4
The equation then becomes x2+3x+(9/4)=17+(9/4).
Solving it further will get you the final answer
The population starts at 2000, so a=2000.
We also know that the population in 3 hours is 1000, so we can setup the equation:
2000 b^3 = 1000
This gets us:
b^3 = 1/2
And taking the cube root of both sides gives us:
b ≈ 0.7937005259841
Rounding that to 4 places, we have:
f(t) = 2000 (0.7937)^t
Answer:
ummm i think its B?
Step-by-step explanation:
Given:
The graph of a quadratic function passes through the points (5,31) (3,11) (0,11).
To find:
The equation of the quadratic function.
Solution:
A quadratic function is defined as:
...(i)
It is passes through the point (0,11). So, substitute
in (i).
![11=a(0)^2+b(0)+c](https://tex.z-dn.net/?f=11%3Da%280%29%5E2%2Bb%280%29%2Bc)
![11=c](https://tex.z-dn.net/?f=11%3Dc)
Putting
in (i), we get
...(ii)
The quadratic function passes through the point (5,31). So, substitute
in (ii).
![20=25a+5b](https://tex.z-dn.net/?f=20%3D25a%2B5b)
Divide both sides by 5.
...(iii)
The quadratic function passes through the point (3,11). So, substitute
in (ii).
Divide both sides by 3.
...(iv)
Subtracting (iv) from (iii), we get
![4-0=5a+b-3a-b](https://tex.z-dn.net/?f=4-0%3D5a%2Bb-3a-b)
![4=2a](https://tex.z-dn.net/?f=4%3D2a)
![\dfrac{4}{2}=a](https://tex.z-dn.net/?f=%5Cdfrac%7B4%7D%7B2%7D%3Da)
![2=a](https://tex.z-dn.net/?f=2%3Da)
Putting
in (iv), we get
![0=3(2)+b](https://tex.z-dn.net/?f=0%3D3%282%29%2Bb)
![0=6+b](https://tex.z-dn.net/?f=0%3D6%2Bb)
![-6=b](https://tex.z-dn.net/?f=-6%3Db)
Putting
in (ii), we get
Therefore, the required quadratic equation is
.