SOLUTION: Write an equation for a polynomial function that satisfies each set of characteristics. extending from quadrant 2 to quadrant 4, two turning points, y-intercept of 1

Algebra ->  Linear-equations -> SOLUTION: Write an equation for a polynomial function that satisfies each set of characteristics. extending from quadrant 2 to quadrant 4, two turning points, y-intercept of 1      Log On


   



Question 1177496: Write an equation for a polynomial function that satisfies each set of characteristics.
extending from quadrant 2 to quadrant 4, two turning points, y-intercept of 1

Found 2 solutions by ikleyn, Edwin McCravy:
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.

According to the context, the plot of the polynomial should be located in the 2nd and 4th quadrants 

with the y-intercept at y= 1,


with no parts in the 1st and/or 3rd quadrant.



A polynomial satisfying such conditions DOES NOT EXIST.


If you mean something different, then the problem should be formulated accordingly.



Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
It doesn't say "with no parts in the 1st and/or 3rd quadrant", it just
says "extending from quadrant 2 to quadrant 4".  It can extend from quadrant
2 to quadrant 4 by passing through quadrant 1 on its way to quadrant 4. 

It might very well look like the graph  below, with two turning points,
and having zeros at, arbitrarily, -3 and 4, and going up on the extreme
right.  So we'll make sure it has a positive leading term.



To have 2 turning points, it must have degree 3 or more.  So let's try to
make it have 3 real zeros.

To have a zero at -3 it must have factor (x+3)

To have a zero at 4 it must have factor (x-4)

It must have another zero between -3 and 4. Let's suppose that third zero
has value a.  So the polynomial must also have a factor (x-a)

It would have degree 3 if it were of the form

p%28x%29+=+%28x%2B3%29%28x-4%29%28x-a%29

and hopefully "a" will turn out to be between -3 and 4.

In order for the polynomial to have y-intercept 1, it must go through (0,1).

So we substitute x=0 and p(0)=1

p%280%29+=+%280%2B3%29%280-4%29%28-a%29=1

%283%29%28-4%29%28-a%29=1

12a=1

a=1%2F12 <--that is between -3 and 4

So such a polynomial would be

p%28x%29+=+%28x%2B3%29%28x-4%29%28x-1%2F12%29
 
If you multiply that out, you get:

p%28x%29+=+x%5E3+-+expr%2813%2F12%29x%5E2+-+expr%28143%2F12%29x+%2B+1

That's what the graph above is of.

Edwin