To solve a problem, we often plug in the given information into algebraic expression and equations.
Answer:
Step-by-step explanation:
This is of the form
![P(t)=a(b)^t](https://tex.z-dn.net/?f=P%28t%29%3Da%28b%29%5Et)
Where P(t) is the ending population, a is the original population, b is the growth rate, and t is time in years. We have everything we need to solve for t.
![80000=40000(1.19)^t](https://tex.z-dn.net/?f=80000%3D40000%281.19%29%5Et)
Let me explain the growth rate quickly. If the exponential function is a growth function, that means (in this particular situation) that we have 100% of the population and we are increasing it by 19%. That makes the growth rate 119%, which in decimal form is 1.19.
Begin by dividing both sides by 40000 to get
![2=(1.19)^t](https://tex.z-dn.net/?f=2%3D%281.19%29%5Et)
To get that t out of its current exponential position, take the natural log of both sides:
![ln(2)=ln(1.19)^t](https://tex.z-dn.net/?f=ln%282%29%3Dln%281.19%29%5Et)
and the rules of logs say we can bring the exponent down out front:
ln(2) = t*ln(1.19)
Divide both sides by ln(1.19) to get t alone:
![\frac{ln(2)}{ln(1.19)}=t](https://tex.z-dn.net/?f=%5Cfrac%7Bln%282%29%7D%7Bln%281.19%29%7D%3Dt)
Doing that calculation on your calculator gives you that
t = 3.9846...
but rounding to the nearest tenth gives you that
t = 4.0 years
Answer:
Step-by-step explanation:
Here, you can use a simple formula.
To find the point of intersection you just put x=0 or y=0.
Because, if a graph intersects x-axis, then at this point y=0
Similarly, if a graph intersects y-axis, then at this point x=0
So, for our given line.
y=-1/4 x +2
when , x=0 , y=-1/4 (0)+2=2
So, the graph intersects y-axis at y=2
when , y=0 ,
then 0=-1/4 x+2
or, 1/4 x=2
or, x=8 [multiplying by 4]
So, the graph intersects x-axis at x=8