I know I have to use Pythagorean theorem but what do I do with (x-4)^2? Reddit 9th grade geometry
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- čas přidán 25. 05. 2024
- How do we solve this right triangle problem with sides x, x-4, and 8 with the Pythagorean theorem? This is a 9th-grade geometry problem from Reddit r/homeworkhelp
Original post / fjoe1xityq
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Red pen is on strike.
I was going to to say he needed to buy a new one, but his stock of them on the shelf to the right doesn’t seem to gone yet!
Haven't watched the video yet, but it looks like the first issue is the person didn't square the x-4 properly. It''s supposed to be x^2-8x+16. x^2+16 would only be true if it was (x+4)(x-4). So, with that information, it's good to solve. We have x^2 -8x+16+64=x^2. Adding the 16 and 64, as well as subtracting x^2 from both sides, we get -8x+80=0. Add 8x to both sides, and we get 8x=80. Divide both sides by 8, and we end up with x=10, which is our answer. And to prove it, we have 10-4=6 for the height. 6^2+8^2=10^2. 6^2 is 36, 8^2 is 64, and 10^2 is 100. 36+64=100 36+64 is 100, so we end up with 100=100 to prove that x=10.
This person sonetimes so absurd all the way
That's all correct, but one thing: x²+16 is not factorable in (x+4)(x-4), because when you have (a+b)(a-b) you get a²-b², and vice versa. Here we don't have a difference between two squares, but the sum of such numbers. You can't factor this in the Real world, but you can still do it in the Complex world:
Consider 16 as -(-1*16); 16 is equal to 4² and the -1 is equal to i² by the definition of i, so we get that 16 = -(4i)². We use this to write x²+16 as x²-(4i)², and by using the formula for the difference of two squares, we get (x+4i)(x-4i).
@@jojodalmangadijojo Yeah, I had a brain fart. It would be x^2-16, not x^2+16
I love his level of patience and not getting frustrated to these silly problems
It's because he's teaching, he's helping these people out and educating them on their mistakes. Some people need more explanation to understand, not everyone can just instantly get it, so you do need to be patient when teaching them.
If u know pytha triplets then its (6, 8 10) done.
Dont know then , put both x having term on one side to get a^2- b^2 ,to get the result instantly.
Thnks
Do we know for certain that 8 is the long leg?
@@pedrogarcia8706 hypotenus is always greater than any of rest two arms.
@@tejpalsingh366 I'm talking about the other leg...
I’m sure the purpose of the problem is to show your work…
@@pedrogarcia8706 all is clear ... Read carefullly
love these videos
I have watched his 100 integrals video , I was thinking how one can do this which is nearly impossible for anyone to do. Salute to his dedication level
I am 43 now and it feels so good to watch your videos, pause before you start solving and see that I still retain SO MUCH from school. And who says Texas students are dumb? I had great teachers, especially geometry. Love you Ms. Haines!!
a+b whole square is equal to a^2+b^2-2ab. 😊😊😊Sir I also want to learn your marker switching while writting on the board
Will you please demonstrate how the monthly principal and interest is calculated on a mortgage? Your method of explanation is so easy to follow and I have learned much!! Thank you.
before watching the video I bet it is going to be a pythag-triple triangle, no way it would work with whole numbers otherwise.
yay! it was, that didn't really help in solving it though.
thank you sir
Yes!
hi can u take a look at the highest level of australian math exam pls? its called mathematics extension 2 and u can find many past papers online from hsc and other schools thx
I have a better way if there is an 8 the hypotenuse is 10
A 345 triangle the whole time
I pesonally don't like the Pythagorean theorem put as "a^2 + b^2 = c^2", as then kids with lower concentration can easily be fooled when a question mixes up the "a,b,c"'s and labels the hypothenuse "a" or "b"...
To me the formula "k1^2 + k2^2 = h^2" is a better one ("k" being kathethes, "h" being hypothenuse), cause it FORCES the kids to identify the three...
You can name the sides any variable you want. Even with k1^2+k2^2=h^2 , it is the same thing if people didn't pay attention they wouldn't know what these variables are.
_kathethethethethewhatnow?_
Base and height.
"Kathethes"? I don't think I've ever seen that word before, and googling it doesn't help.
@@Steve_Stowers side of the right triangle. From Greek. Aka "cathetus" in Latin. Used in math all over.
This is giving me flashbacks of hating high school.
Do students from US really don't know that? In Europe literally everyone in 9th grade can do it.
I knew plenty of people in England who wouldn't get this.
@@creamwobbly exacly - Great Britain and USA are very similar 😀
That's what happens when u drink flouride water lol