SOLUTION: How many positive real zeros does the funtion f(x) = x4 + x3 - 7x - 1 have?

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Question 3694: How many positive real zeros does the funtion f(x) = x4 + x3 - 7x - 1 have?
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
graph%28300%2C300%2C-1%2C5%2C-10%2C10%2Cx%5E4+%2B+x%5E3+-+7x+-+1%29

Graphing this, gives a root just less than zero (so ignore that), and one between 1 and 2...so the answer looks to be 1 positive root

You can find the sign of f(0), then a few values of x, to semi-proof this finding...as x increases, so the x%5E4 term will dominate hence the curve will not turn back and cross the x-axis again.

jon.