The function is:
f ( x ) = x² - x - 72
This is a quatdratic function. So we can find the zeroes of the function with the formula:
x 1/2 = ( - b +/- √(b² - 4 ac) ) / ( 2a )
And we have: a = 1, b = - 1 and c = - 72
x 1/2 = ( 1 +/- √((-1)² - 4 · 1· ( - 72 )) ) / 2
x 1/2 = ( 1 +/- √( 1 + 288 ) ) / 2
x 1/2 = ( 1 +/- √289 ) / 2
x 1/2 = ( 1 +/- 17 ) / 2
x 1 = ( 1 - 17 ) 2 = - 16 / 2 = - 8
x 2 = ( 1 + 17 ) / 2 = 18 / 2 = 9
Answer: The zeroes are - 8 and 9.
If they are growing 80% for every twodays, it would be 40% for every one day.
Bacteria after 9 days = 212 * 9 * 40 / 100
= 763.2
To round up, the population of bacteria after 9 days would be 763, with a growth rate of 80% for every two days.
It's pretty simple! So it looks like you are learning proportions. You would cross multiply to achieve your answer.
First, let's do your first problem:
2 12
--- = ----
5 n
You would take 5 and multiply it by 12 and get 60! Then you would do the same with 2 times n, giving you 2n (because you do not know what n represents YET.)
Now you should have this:
60=2n OR 2n=60
We must isolate our variable, in order to do that, get rid of two! But how? You would do this by dividing 2n by 2. Yet in equations, when you do something to one side, you must do it to the other because they must be EQUAL! (hence the "equa-" in equation)
2n=60
--- ---
2 2 DIVIDE 2 into 60
----------
n= 30 Simplify!
Your final answer for the first question is n= 30!
The square root of 150 is 12.2474487139. The square root of 136 is 11.6619037897. And your welcome :)
Answer:
x=6
Step-by-step explanation:
