Can someone show me how to find the answer please?
What are the possible number of positive, negative, and complex zeros of f(x) = 2x^3 – 5x^2 – 6x + 4 ?

Question

Can someone show me how to find the answer please?
What are the possible number of positive, negative, and complex zeros of f(x) = 2x^3 – 5x^2 – 6x + 4 ?

precal · Answer

look at the graph, the highest power is 3 therefore you have 3 solutions

precal · Answer

http://www.wolframalpha.com/input/?i=graph+2x%5E3+%E2%80%93+5x%5E2+%E2%80%93+6x+%2B+4 notice how it crosses the x axis three times, therefore you have 3 solutions

precal · Answer

2 positive and 1 negative (look at where it crosses the x axis)

anonymous · Answer

Can you show me how to find it without looking at a graph?

precal · Answer

do you know how to do synthetic division? or p/q theorem? usually algebra II concepts

anonymous · Answer

Yeah I know how to do synthetic division.

precal · Answer

http://www.wolframalpha.com/input/?i=graph+2x%5E3+%E2%80%93+5x%5E2+%E2%80%93+6x+%2B+4 not a nice function to solve

precal · Answer

you could use factoring by grouping, do you know how to do that?

anonymous · Answer

Yes I do but how will that help?

precal · Answer

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doesn't work, we can do that