Question 627996
The intermediate value theorem is basically this:  If a point on a continuous curve has a point above a line, and it has a point below a line, then it must have a point on the line.  This means that if there's a polynomial with a value above y=0 and below y=0 then it must have a zero in that interval.<P>
The bottom line is: when given an interval and a polynomial check the low value and high value.  If one is positive and the other negative then there must be a zero within that interval.<P>
7x^4-2x^2+4x-1 for x=0 is -1
7x^4-2x^2+4x-1 for x=-3 is  7*81 -18 -12 -1 = +<P>
This polynomial has a zero in the given interval.
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