A-Level Maths: H7-01 Differential Equations: Introducing Differential Equations

[sabrinaislam]

You basically made me understand something that I have struggled to understand for days just within 4 mins. Thank you so much!

[Just_Shaun]

These videos are fantastic for simplifying the “wordiness” of the textbooks. Very handy for revision.

[benhallo]

Your knowledge of maths is actually beautiful

[karotic]

how do you know whether you’re supposed to use differential equations to solve an integral

[GCSEALevelMaths]

Excellent video sir well explained good job.

[Zahra-htec]

hello, is the content in differential equations playlist the same for CAIE ?

[natedixon]

If I pass tomorrow you’re the reason why

[wilhelmvongreim]

Hello sir, there is a differential equation question I found on Physics and Maths Tutor and I can’t quite make sense out of its answer.
The Question and its given answer is as follows:
 
“The mass of a radioactive substance at time t is decaying at a rate which is proportional to the mass present at time t. Find a differential equation connecting the mass m and the time t.
dm/dt∝-m
dm/dt=-km, where k is the positive constant of proportionality
∫1/m dm = ∫-kt dt
ln|m|=-1/2kt^2+lnA
ln|m/A|=-1/2kt^2
m=Ae^-1/2kt^2”
 
Between the second and the third step, where did the “t” on the right hand side come from? Is this procedure incorrect, or did I miss something?
(Sorry for the bad English, it isn’t my first language).

[johnsmith-hsoi]

Is this all that would be covered on the AQA course