Hi guys, in the last class you learned what a function is, didn't you? And in this class you will learn how to calculate the numerical value of a function, let's go? So welcome to another class on the Gis channel, and before I explain how to calculate the numerical value of a function, take the opportunity to subscribe to the Gis channel and leave a thumbs up.
So let's remember a little something like what is the notation of a function? Do you remember? So what a function looks like here: f as a function of If you haven't watched it, go back and you'll have a good performance here.
So guys, for us today to calculate this numerical value that I brought, first let's write down what is the law of formation that represents the perimeter of this square, I even highlighted it here, people, law of formation, law of correspondence, it's the same thing, okay, I just used other words to represent. So perimeter, folks, what is perimeter even though I want to represent the perimeter of this square, perimeter of the square is not the sum of the four sides of the square, I know that each side measures x, right, so the sum of the four sides will be x + x + x + x which results in 4x so the perimeter of the square results in 4 times x, but then here I wrote it, well formally, I didn't put it within the concept of the function notation and how will it be within the concept of the notation there so I I'm going to use the perimeter by the letter P, so the perimeter depends on who measures the side because the side is not x, so this perimeter, which is the dependent variable, is a function of the measurement of the right side, which is = 4x, but Gis this here is We already saw it in the last class when I talked about the salesman's salary and when I talked about the price to be paid at the computer repair Ok, just so you can remember, I also did this numerical value in class 1, I don't know if You paid attention. Well, now that I know that this is the formation law that our function that represents the perimeter of this square but guys, what is a numerical value now the numerical value is when I change this value of X here for a number, so for For example, if you see it written like this: P (8)= , what is P of 8?
What did I do here guys? I changed the value of X to 8, okay? So what will the result here of the perimeter look like?
It will be four times in place of this x, I also change it to 8. So see that what I put here I also change here, right, this is calculating the numerical value, people, it is changing the value of X for a number but let's not just talk about the value of be 32, which is the same thing as you see here, ox is worth 8, 8 plus 8 from 16 with eight more plus 8 16 24 32, gives 32. But what if I changed it for example, op now means ox, right?
changing x , the when the measure of my square is 5, right, because x represents the measure of the square, right = 20, so guys, this is calculating the numerical value of the function, right, let's do other examples, now, shall we? Look who I brought today, it's not pacocha, okay, it's the function robot because the function robot because now we're going to do the calculation of the numerical value in a different way because in case you didn't understand in the previous example, now I'm going to give you a little help If you understand, let's go then? Oh, so I brought here the function fx = x + 3, this is the function, I brought it ready, I didn't bring any situation for us to represent, I brought it ready, because the focus of this class is to find the numerical value.
So let's pretend that our robot function, it calculates, I enter the value there, it gives the result to us, okay, that's it, we're the ones who are going to have to do it, right? So, let's pretend that I gave the robot the number 6, what is the robot going to do with this number 6, you know, the robot is going to take this number 6 and put it in the place of F, no, right guys, it's going to put this value of six in place of X then he will do the processing there he will do his calculation and he puts this six in place of the x, right? because he wants to calculate what he wants to calculate F when I replaced the the 6 in place of the X will then be six plus 3 and 6 + three are nine.
So this means that when I assign this value six to the robot it will give me the answer 9. This means that the value of the function is nine numerical value, right guys, how are you? Shall we do another example now?
So if I now assign it to the robot, hey, my robot doesn't want to work here, the value is now -4 guys, I'm going to assign the value -4. What does it mean to assign this value -4, it means that I am now going to calculate the value of -4, can you see that I am changing here I changed the x to six and here I am changing the X to -4, I am assigning a value to the right x and Then I will have it that will be -4 plus three and -4 plus three. What is the result that the robot will give me here, have you ever imagined -4 plus three are minus 1 because if I owe four reais and I have three I owe minus one, I owe one then the robot would give me the result -1 numeric value of the function when I changed the X to -4.
And now let's do something that's a little more difficult, let's see if you can do it. I'll now put the value for doubt the fraction I don't believe. So go back to class and I explained all the fraction content, there's even a playlist ready with everything for you to answer your questions, ok?
And now, how am I going to calculate the numerical value of this function when I change the X to 3 /4 or three quarters. So what will its assembly look like, it will be 3/4 instead of x, right because I'm looking at this function here, you noticed that I'm looking here, right, plus three, what will be the result that the robot will give me, will bring it, let's see then robot will release it for me 15/4. Is 15/4 right?
Let's do it, let's see if it will work, so here, I'm going to do it side by side, I have to add 3/4 with 3 so I can add 3 quarters with 3, I'm going to put the denominator 1 at the bottom here, okay, and then we're going to take the LMC, LMC between 4 and 1 is 4, and then I do the equivalence process from 4 to 4 was times 1, so here remains times one which gives three from one to four was times four then multiply by 4 which gives 12 and now to I add this fraction then I keep the denominator which is already the same and I add the numerators three plus 12 three plus 12 which are 15 so I will get the numerical value of 15 quarters so this means that our robot got one more right this robot is fine Smart, he's well trained, OK guys? Now let's do another example, I'm going to make the function a little more difficult now. Let's go?
Guys, now I brought another function look here fx = - 4x plus one I changed the function a little now and then we are going to calculate the numerical value of this function when I assign the value to x equal to negative seven then it will look like this f, pen red, you know, I forgot to pick it up, minus seven, right? Same, then Gis needs to keep doing this stupid thing every time, of course we don't do it mentally like a robot, the function does it, it plays the value and it calculates it correctly, I'm doing it to explain it, right? If you understand well, then it will be F - 7 = -4 Times minus seven plus one, o sign rule in multiplication 4 x 7= 28 minus with minus plus, 28 + 1= 29.
So this means that the numerical value of this function When I change the X to minus 7 it will be 29 so the robot would assign us 29 right? Now let's do another example, so let's put it now, I'm going to do it here and you do it straight away, okay, just to check with me, oops, upside down, it's not possible, right? Let's now assign the value to x = 18.
So that means it will be f(18) = - 4 x 18, hey, I didn't change the color, another 1 to this one will remain without changing the color in people -4 x 18 a 4 x 18, 18 36 36 72 I doubled 36 it gave 72 but with this negative this is positive here it will give - 72 and minus 72 plus one will result in minus 71 so here the robot would give us minus 71, numerical value I found once again. Let's now put the fraction value for x, so let's put that x is worth 5/8 now, so it means that I will have f (5/8) eighths, right, changing x = - 4 x 5/8 plus 1, how do I start doing this multiplication now, you know, I put one below here, I multiply the numerator with numerator denominator with denominator. So this means that it will be minus 20/8, this minus sign is not here, this minus sign is here, right, folks, plus one and for me to do this addition subtraction, put one below here and it would do the mmc, right, so let's go do here, minus 20/8 plus 1, go up by 1, right, remove the MMC which gives 8 from 8 to 8 was times 1 so here is 20 from 1 to 8 was times 8 so here is 8, so I keep the denominator 8 and here goes get minus 12 because if I owe 20 and I have eight I owe 12 and guys, I can simplify this here by four so it will result in minus t3/2.
So that means the robot would assign us the numerical value of minus 3/2, okay guys? So you managed to understand how you calculated it, right? Robot function here helped a lot, didn't it?
And then, people, in your activities, you can do it straight away, okay, you can calculate it mentally and if you have any difficulties, you can also do the entire process step by step. Look, I didn't write it here, I'm going to write it to be complete minus 3/2, now it's complete in this account, right? So if you liked the class, managed to understand what Gis wanted to explain about the numerical value of a function, leave a thumbs up and take the opportunity to subscribe to the channel and I'll see you in the next class, bye.
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