Hi there! First and foremost, I would like to thank you for producing these amazing videos, they really are coming in clutch. Secondly, I was looking over your Edexcel Applied Year 2 (A-Level Maths) playlist, and I couldn't find a video for exercise 7A. Is that because we don't need to know how to do that exercise?
You’re very welcome! Pleased they are helpful. Yes, Exercise 7A is excluded because in the videos in the playlist for Forces I set questions which are similar/better! The content is covered in videos 1 and 6 of this playlist ua-cam.com/play/PL0SSkmc4r_BaoOuDvu6nXuC-AkO74XfRt.html I teach Forces in a different order to the textbook as I think it’s badly organised, which is why I have adjusted it in this way! Hope that helps. Feel free to ask any questions any time 👍🏼
Hi again, thank you lots for putting up with all my questions - I hope you don't mind me asking one more. What's confusing me is when we differentiate - lets say 6x^2 - it becomes 12x. So we multiply and minus one from the power. Here 4:57, we multiply by the power, but we aren't subtracting one? How does that work or have I got the wrong idea here
will exponential modelling always involve an equation in terms of e or could it be in the form ab^t. In the revision guide they only have questions for exponential modelling involving e so can I assume this will be the case for exams as well?
@@BicenMaths thanks for the reply sir, I just wanted to ask how you would know in which case to use e or the form ab^t. For example in this question: In a simple model, the value, £V, of a car depends on its age, t, in years. The following information is available for car A • its value when new is £20 000 • its value after one year is £16 000 (a) Use an exponential model to form, for car A, a possible equation linking V with t. the equation should be in the form that uses e but there's no reference saying to use this form. Thanks
@h.d8334 you can choose to use either, they will both work! They will produce different equations but both are considered exponential and would give the same outputs for the same given inputs! I personally sticks with Ae^kt as my go to form.
3:27 sir i though if the power is below 1 it is exponential decay or does that get cancelled out by the fact that the coefficent or ''base'' is also below 1?
That's only the method for differentiating things of the form ax^n. If it's not that form, it likely won't bring the power down and reduce by one - you'll see more of this in Year 2, so don't assume they'll all follow the Year 1 pattern!
@@BicenMaths oh ok, also sir how many hours of maths revision do you think an A* aiming student should try to do per wwek from the beginning of year 13
@@jefking2158 It's really hard to say as will depend on each individual - but working hard at the beginning of the year will develop good habits, and reduce your stress levels throughout the whole of Year 13 - you will feel more prepared for mocks, and the real thing, so do as much as you can! Don't over do it, but pushing yourself will develop great habits. Good luck!
@@jefking2158 if you are using the right revision methods, I'd say between 7-10hrs of active focussed revision a week for maths, but some people might need to do more and some people don't need to do as much
hey sir, how come for the first question you changed the time( 1 year) to 0.5 but for the second question you didnt make any changes to the number of days
because in the first question, it says it is measured in t years, so you have to make 6 months measured into years which is 0.5 years. but for the second question, t is measured in the number of days, so you dont need to change anything for that one
In 2:09 question 5b you were differentiating the initial equation so weren’t you supposed to have multiplied 25 by -0.05t. -0.05t is the whole power of e. I don’t understand why you ended up multiplying 25 by -0.05.
very helpful indeed. I was gojng mad over these exponential modelling questions in exams only to realise the book is awful at them!
Hi there! First and foremost, I would like to thank you for producing these amazing videos, they really are coming in clutch. Secondly, I was looking over your Edexcel Applied Year 2 (A-Level Maths) playlist, and I couldn't find a video for exercise 7A. Is that because we don't need to know how to do that exercise?
You’re very welcome! Pleased they are helpful. Yes, Exercise 7A is excluded because in the videos in the playlist for Forces I set questions which are similar/better! The content is covered in videos 1 and 6 of this playlist ua-cam.com/play/PL0SSkmc4r_BaoOuDvu6nXuC-AkO74XfRt.html
I teach Forces in a different order to the textbook as I think it’s badly organised, which is why I have adjusted it in this way! Hope that helps. Feel free to ask any questions any time 👍🏼
Hi again, thank you lots for putting up with all my questions - I hope you don't mind me asking one more. What's confusing me is when we differentiate - lets say 6x^2 - it becomes 12x. So we multiply and minus one from the power. Here 4:57, we multiply by the power, but we aren't subtracting one? How does that work or have I got the wrong idea here
Here the power is a function of the variable t, e^t functions differentiate differently. Check this out: ua-cam.com/video/qqLVaUIdGAg/v-deo.html
for the last question can you say that the price of car may not decrease constantly at the same rate and might change after fews years??
Yes! That would be accepted
will exponential modelling always involve an equation in terms of e or could it be in the form ab^t. In the revision guide they only have questions for exponential modelling involving e so can I assume this will be the case for exams as well?
No, I expect that there could be both forms, definitely be prepared for both!
@@BicenMaths thanks for the reply sir,
I just wanted to ask how you would know in which case to use e or the form ab^t. For example in this question:
In a simple model, the value, £V, of a car depends on its age, t, in years. The following information is available for car A
• its value when new is £20 000
• its value after one year is £16 000
(a) Use an exponential model to form, for car A, a possible equation linking V with t.
the equation should be in the form that uses e but there's no reference saying to use this form.
Thanks
@h.d8334 you can choose to use either, they will both work! They will produce different equations but both are considered exponential and would give the same outputs for the same given inputs! I personally sticks with Ae^kt as my go to form.
3:27 sir i though if the power is below 1 it is exponential decay or does that get cancelled out by the fact that the coefficent or ''base'' is also below 1?
You're correct that it was cancelled out by the base between 0 and 1! They have the same effect.
At 12:50 when you differentiate why dont you bring the power down by one?
That's only the method for differentiating things of the form ax^n. If it's not that form, it likely won't bring the power down and reduce by one - you'll see more of this in Year 2, so don't assume they'll all follow the Year 1 pattern!
@@BicenMaths oh ok, also sir how many hours of maths revision do you think an A* aiming student should try to do per wwek from the beginning of year 13
@@jefking2158 It's really hard to say as will depend on each individual - but working hard at the beginning of the year will develop good habits, and reduce your stress levels throughout the whole of Year 13 - you will feel more prepared for mocks, and the real thing, so do as much as you can! Don't over do it, but pushing yourself will develop great habits. Good luck!
@@jefking2158 if you are using the right revision methods, I'd say between 7-10hrs of active focussed revision a week for maths, but some people might need to do more and some people don't need to do as much
@@JoseMourinho-tl5ow did you get an A*. And is that outside or including lesson time
hey sir, how come for the first question you changed the time( 1 year) to 0.5 but for the second question you didnt make any changes to the number of days
because in the first question, it says it is measured in t years, so you have to make 6 months measured into years which is 0.5 years. but for the second question, t is measured in the number of days, so you dont need to change anything for that one
Is there any way I could download the slides ur using for this video as a pdf.
Yep, go to my Google Drive (in the About section on my channel) then go to blank lesson slides.
In 2:09 question 5b you were differentiating the initial equation so weren’t you supposed to have multiplied 25 by -0.05t. -0.05t is the whole power of e. I don’t understand why you ended up multiplying 25 by -0.05.
You don’t multiply by the whole power, just the coefficient of that power!
@@BicenMaths if that’s the case, then what if the power of e is a whole number. And there is no coefficients
Like e^2? Well that’s just a constant (i.e. it’s just a number you could find on your calc), and constants differentiate to 0!
And you were also supposed to decrease the power of e by 1 while differentiating.
Nope, that’s not how you differentiate exponentials. That only applies to polynomials!