We will learn how to solve these types of equations as we continue in our study of algebra. In fact, many polynomial equations that do not factor do have real solutions. This does not imply that equations involving these unfactorable polynomials do not have real solutions. We have seen that many polynomials do not factor. In general, for any polynomial equation with one variable of degree \(n\), the fundamental theorem of algebra guarantees \(n\) real solutions or fewer. Notice that the degree of the polynomial is \(3\) and we obtained three solutions. X plus negative five, which is the same thing as x minus five, times x plus negative two, which is the same thing as x minus two. Whole thing as equal to negative three times So let's see A could beĮqual to negative five, and then B is equal to negative two. Have to have the same sign 'cause their product is positive. Where if I were to add them I get to negative seven, and if I were to multiply And now let's see if weĬan factor this thing a little bit more. Three out of negative 30, you're left with a Three from this term, 21 divided by negative Out a negative three out of this term, you're just Three, what does that become? Well then if you factor So instead of just factoring out a three, let's factor out a negative three. You can do it, but it still takes a little bit more of a mental load. Out on the x squared term still makes it a little bit confusing on how you would factor this further. You could do it this way, but having this negative Seven x, so plus seven x, and then negative 30 dividedīy three is negative 10. This is the same thing as three times, well negative three x squared divided by three is negative x squared, 21 x divided by three is Greatest common factor? So let's see, they'reĪll divisible by three, so you could factor out a three. Pause the video and see if youĬan factor this completely. So let's say that we had the expression negative three x squared And now I have actuallyįactored this completely. That as x minus three, times x plus one, x plus one. They are used in countless ways in the fields of engineering, architecture, finance, biological science, and, of course, mathematics. For example, equations such as \ (2x2 +3x10\) and \ (x24 0\) are quadratic equations. So I could re-write all of this as four times x plus negative three, or I could just write An equation containing a second-degree polynomial is called a quadratic equation. Plus one is negative two, and negative three times So let's see, A could beĮqual to negative three and B could be equal to one because negative three A plus B is equal to negative two, A times B needs to beĮqual to negative three. I get a negative value, one of the 'em is going to be positive and one of 'em is going to be negative. I get negative three, since when I multiply That add up to negative two, and when I multiply it Now am I done factoring? Well it looks like IĬould factor this thing a little bit more. And if I factor a four out of negative 12, negative 12 divided byįour is negative three. Of negative eight x, negative eight x dividedīy four is negative two, so I'm going to have negative two x. Out of four x squared, I'm just going to be So I could re-write this as four times, now what would it be, four times what? Well if I factor a four They're not all divisible by x, so I can't throw an x in there. So let's see, they'reĪll divisible by two, so two would be a common factor, but let's see, they'reĪlso all divisible by four, four is divisible by four,Įight is divisible by four, 12 is divisible by four, and that looks like the Try to find the greatest of the common factor, possible common factors There any common factor to all the terms, and I So the way that I like to think about it, I first try to see is So factor this completely, pause the video and have a go at that. See if we can try to factor the following expression completely.
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