Question #490b3

1 Answer
Jan 6, 2018

Please see below.

Explanation:

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A polynomial of degree #4# has a general form of:

#y=ax^4+bx^3+cx^2+dx+f#

It has four roots, i.e. if you solve for #x# you will have #4# answers. These roots, if they are all real numbers, are where the graph of this function crosses the #x#-axis.

So, you can pick #4# values of your choice between #-10# and #10# and make them the roots of your polynomial. Let's pick:

#x=-4, -1, 2, 5#

Then, you can write your function as follows:

#y=(x+4)(x+1)(x-2)(x-5)#

After multiplying them through and removing parentheses, you get:

#y=x^4-2x^3-21x^2+22x+40#

Here is its graph:

enter image source here

As you can see. the graph crosses the #x#-axis at the #x# values you picked.