#FACTORS OF QUADRATIC EQUATION PLUS#

And then if we take negativeĨ plus 7, that is equal to negative 1, which is exactly theĬoefficient right there. So if we take negativeĨ times 7, that's equal to negative 56. Sum is negative, tells me that the larger of these two should

Positive, and one of these has to be negative. Out into my brain, because they're very close Jump out in your brain, we just learned this in Jump out in my brain- and I don't know if they One is going to be positive, and one is going to be Numbers have to be minus 56, have to be negative 56. Just to really get well honed this skill. Plus negative 7, but that'd be equal to negative 5, so that We're done! That worked! I mean, we could have tried 2 This in a different color- if I do negative 2 plus 7, Now what about 2 and 7? If I do negative 2- let me do And 1 plus negative 14 isĮqual to negative 13. So let me write all of theĬombinations that I could do. Going to try out things- 1 and 14, negative 1 plusġ4 is negative 13. Two, do I get 5? So if I take 1 and 14- I'm just Or I'm really kind of taking the difference of the When I add them, if one is positive and one is negative, And when I add the two, a plusī, it'd be equal to 5. Is positive, and one of them is negative. Negative, right? a times b is equal to negative 14. Minus 11x, plus 24 is going to be equal to x minus Work out, right? Because we have a negativeģ and negative 8? Negative 3 times negative 8 So when you look at these,ģ and 8 jump out. Let's take the negative of both of those. Two factors, when I add them, should I get 11? And then we could say, Multiply these- well, obviously when I multiplyġ times 24, I get 24. Times 24, 2 times 11, 3 times 8, or 4 times 6. And they both can't be positive,īecause when you add them it would get youĪ positive number. Remember, one can't be negativeĪnd the other one can't be positive, because the Their product is positive, tells me that both aĪnd b are negative. The fact that their sum is negative, and the fact that Now, if when I add them, I getĪ negative number, if these were positive, there's no way IĬan add two positive numbers and get a negative number, so Need to be positive, or both of these need to be negative. Let's up the stakes a littleīit, introduce some negative signs in here. Out, and see that this is indeed x squared plus This would be equal to x plus 5, times x plus 10. Let's try out these numbers,Īnd see if any of these add up to 15. So what could a and b be? Let's think about theįactors of 50. You do, you're going to see that it'll start toĬome naturally. And this is going to be a bit ofĪn art that you're going to develop, but the more practice Numbers that, when I multiply them I get 50, and when Plus 10x, plus- well, I already did 10x, let's do aĭifferent number- x squared plus 15x, plus 50. Whatever's my constant term, myĪ times b, the product has to be that. You should put it in that form, so that you canĪlways say, OK, whatever's on the first degree coefficient, And of course, this has toīe in standard form. You take their product, have to be equal to 9. Say, all right, what two numbers add up to thisĬoefficient right here? And those same two numbers, when Leading coefficient on this quadratic is a 1, you can just This, when the coefficient on the x squared term, or the Videos, you'll see that it is indeed x squared plusġ0x, plus 9. Out, using the skills we developed in the last few So we could factor thisĪs being x plus 1, times x plus 9. So a could be equal to 1, andī could be equal to 9. You'll have 3 plus 3- that doesn't equal 10. So what are the factors of 9? They're 1, 3, and 9. And normally when we'reįactoring, especially when we're beginning to factor, What are the factors of 9? What are the things that aĪnd b could be equal to? And we're assuming thatĮverything is an integer. Match this to that? Is there some a and b whereĪ plus b is equal to 10? And a times b is equal to 9? Well, let's just think about Middle coefficient on the x term, or you could say theįirst degree coefficient there, that's going to be This is the product of two binomials, we see that this Plus- I can write it as b plus a, or a plusī, x, plus ab. In the middle right here, because they're bothĬoefficients of x. X squared, plus x times b, which is bx, plus a times x, Two things, what happens? Well, we have a little bit What happens if we were to take x plus a, and multiply How do we do that? Well, let's just think about Quadratic expression, x squared plus 10x, plus 9. In this case, in all of theĮxamples we'll do, it'll be x. Have a variable raised to the second power. Polynomial, or just a quadratic itself, or quadraticĮxpression, but all it means is a second degree polynomial. Bunch of examples of factoring a second degree polynomial,

Factors of quadratic equation