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There are three given points for this particular polynomial. Therefore, the minimum degree of this mystery polynomial must be of degree 2. The polynomial could be of a higher degree, but there is no need to consider such an option.

 

Since the polynomial is of degree 2, this polynomial is a quadratic. Quadratics are of the form . Let's use the information given to use to determine the equation. Normally, this would be a nasty three-variable system of linear equations, but we can avoid this if we recognize that the y-intercept is already given.

 

Since the y-intercept is already given at the point (0, 5), . Unfortunately, we cannot take any more shortcuts beyond this point.

 

 

Now, let's solve this system of two variables. Unfortunately, it is already clear that this system will be an algebraic nightmare, but we will manage and perservere. I will use the elimination method and eliminate b first as that is probably the simplest one to do at this point.

 

 

Ok, let's now solve for b. Neither equation looks as if there will be an easy substitution. I chose equation 1, but either one will do.

 

 

Therefore, the equation of this polynomial is as follows: . Yikes! This one is awful to do by hand.

Feb 4, 2021
 #1
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This is a system of equations. Let's try and solve it.

 

While it is possible to solve for x or y and then do direct substitution into the remaining equation, I noticed a possible shortcut that is worth knowing for future algebraic problems like this one. This may not save too much time for this particular problem, but I figured it would be to your benefit if I showed this strange substitution to you.

 

 

I squared equation 1 and rearranged a few terms. To the untrained eye, this may seem to complicate matters unnecessarily, but I am setting up a creative substitution.

 

 

Let's use this substitution in equation 1 and solve it.

 

 

This quadratic is neither easy nor factorable. I will result to the quadratic formula for this particular question.

 

 

Let's find the corresponding y-values by substituting these values for x into .

 

 

There are two coordinates of intersections. One is at , and the other is at 

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Feb 4, 2021

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