What is the value of c so that 9x^2 + 15x + c = 0 has one rational solution
2 answers:
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Answer:
C
Step-by-step explanation:
So, we started out with 2,400 black rhinos.
And we know that they are declining at a rate of 10% per year.
In other words, each subsequent year will only have <em>90%</em> of the previous year's rhinos.
Therefore, our function is:
We can do some elimination first.
First, the starting point or y-intercept <em>must </em>be 2400 since that's the number of rhinos we started out with.
Therefore, we can eliminate A and D.
From the remaining choices B or C, we can technically also eliminate B. This is because from our function, we know it's exponential decay, and exponential decay is <em>not</em> a straight line.
However, to double check, let's check the population after 10 years using our function. So:
Use a calculator:
So, after 10 years, the population should be around 840.
B is definitely <em>not</em> 840 (at x=10). However, C is right around it.
Therefore, we can conclude that C is the right answer.
And we're done!