Differentiation (Perimeter/Area/Volume Problems)

[@Amber_malik776]

most underrated revision channel ever, good job once again sir, u have helped me understand a topic I really struggled with, what a legend.

[@rurzee]

never understood this well enough, but you explained it so well! Hopefully ill smash this question if one comes up tomorrow :)

[@1stClassMaths]

That's very kind!

[@red_sun_sundowner]

i learnt this a while ago and couldn't remember how to do it - ty for the quick and informative video

[@aumbs]

THANK YOU, life saver fr!!

[@BernadetteKayi]

A day before my exam, thank you so very much ❤

[@lilysmith1673]

thank youuu!

[@xenonn5499]

I ve been searching for help in this topic , thank youuuu

[@1stClassMaths]

You're welcome 😊

[@edwin_a]

You're such a lifesaver, you thought about doing videos for A-level maths content?

[@1stClassMaths]

One day yes

[@speedysloth361]

in 4:11 couldnt you just complete the square

[@1stClassMaths]

You can yes, however worth noting: - this question says using differentiation. If that happens in the exam you'd not score marks. - CTS is helpful for quadratics but you may see problems in the future where the resulting equation is a higher power so differentiation will be the right approach.

[@memoriess-bx5lz]

would there ever be a question that asked for the minimum point? would u just do the same thing? tysm!

[@1stClassMaths]

You can find the minimum of a quadratic if the equation gives a “U shape”, however in these it will not. The minimum value for these will just be zero i.e. all lengths are zero and the shape does not exist.

[@salamisupplier]

for the last part on the first example when you are working out the maximum value, why do you do da/dx = 0, isnt that for stationary points not for maxima points? i thought maxima points is when x is less than 0

[@1stClassMaths]

Maxima are stationary points. To find a maximum point you must first look for a stationary point.

[@lenagalyo7059]

i want to hug you

[@Colea1010]

😮