Monthly Archives: March 2018

Week 6- Discriminants/Quadratic Equations

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The discriminant is a number that shows if the value of x is rational/irrational/how many roots it has.

The formula we use to find the discriminant of a quadratic equation is b²-4ac

ex: 2x²-10x+3=0

The first step is to identify the values of a,b and c:

a=2

b=-10

c=3

We will then plug these numbers into the formula:

-10²-4(2)(3)

100-24

=76

The discriminant for 2x²-10x+3=0 is 76. This means that this quadratic equation has 2 irrational roots. This is because the equation is positive yet not a perfect square.

 

Week 5- Factoring polynomials

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This week, we spent reviewing factoring polynomials.

ex: x²+12x+20

Notice that this equation is rational. This means that we can easily factor this equation. To factor this equation, we want to look at which 2 numbers multiply into 20 AND add into 12. If we look at the numbers 10 and 2, we see that if you multiply them, they equal 20 and when you add them, they equal 12. This means that these 2 numbers will be used to factor. (x+10) (x+2) is the answer once factored. Once expanded, the product will be x²+12x+20. This means is a good way to make sure the factoring was done properly.