in 5 min, Peter completed 2 math problems. Yvonne says he did 3/5 of a problem each minute. is she correct? Explain.
2 answers:
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one way would be to factor
I can't factor it so we will have to use Descartes' Rule of Signs which is helpful for finding how many real roots you have
it goes like this:
for a polynomial with real coefients, consider .
after arranging the terms in decending order in terms of degree, count how many times the signs of the coeffients change direction and minus 2 from that number until you get to 1 or 0. that will be the number of even roots the function can have
We have (-, -, +, +). the signs changed 1 times, so it has 1 real positive root
to get the negative roots, we evaluate f(-x) and see how many times the root changes
signs are (-, -, -, +). there was 1 change in sign
so the function has 1 real negative root
a total of 2 real roots
a function of degree can have at most,
roots
our function is degree 6 so it has 6 roots
if 2 are real, then the others must be complex
6-2=4 so there are 4 complex roots
you can also show that there are only 2 real roots by using a graphing utility to see that there are only 2 real roots
Answer:
You have to buy more than 20 books to make Cool Cover Bookstore club a better deal.
Step-by-step explanation:
Given that:
Fee charged by Fun Reads Bookstore = $40
Charges per book = $5
Let x be the number of books.
A(x) = 5x+40
Fee charged by Cool Covers Bookstore = $100
Charges per book = $2
B(x) = 2x+100
For making Cool Cover Bookstores club a better deal,
B(x) > A(x)
2x+100 > 5x+40
2x-5x > 40-100
-3x > -60
Dividing both sides by -3
Hence,
You have to buy more than 20 books to make Cool Cover Bookstore club a better deal.