Question

For 3x9 –7x6 + 4x3 + 15 = 0, state the number of complex roots, the possible number of real roots, and the possible rational roots.

Answer 1

Start counting. You signs are +-++ How many changes do you see?

Answer 2

4

Answer 3

No, you see four signs. It starts positive and changes to negative. That's one sign change. How many more CHANGES are there?

Answer 4

2

Answer 5

Since you are in the habit of answering with one character, I have to clarify, how many sign changes do you see in +-++? Please answer in a sentence.

Answer 6

i see 2 sign changes

Answer 7

This tells us what about the possible number of positive, real roots?

Answer 8

well i know there are a possible of 9 complex roots and im not sure about real roots @tkhunny

Answer 9

is there 2 @tkhunny

Answer 10

No, there ARE 9 Complex Roots, counting multiplicities and Real Numbers
With 2 sign changes in f(x), we now know that there CAN BE 2 positive Real roots. If it is not 2, it must be different by a multiple of 2. So, 2 or 0 Positive Real Roots.

Okay, now state f(-x). What does that thing look like?

Answer 11

@iGreen

Answer 12

So, you're not going to produce f(-x)?