Help with differentiation

[radiant lily]

how to differentiate using first principles. im stuck here

[acoustic mulch]

plug the function into the definition of the derivative

and then youll get two square roots in the numerator of the form a -b

then you can multiply the top and bottom by a+b to use difference of squares

then stuff in the numerator should cancel, and you can finally take the limit as h goes to 0

[radiant lily]

yeah i did the same steps but the stuff in the numerator does not get cancelled

i know the answer bcos i did it using chain rule

but its difficult to do using first principles

can u send me a screenshot of ur working if possible

it would help me a lot

[acoustic mulch]

did you get to this point

[radiant lily]

This is what I did so far

[acoustic mulch]

well you did cancel

now you just need to take the limit as h approaches 0

also im not sure if some of the algebra towards the bottom of the page is correct

but it doestn matter because the last three steps are unnecessary, you can take the limit right after that 4th to last step

[radiant lily]

OMG

Thanks so much

I got it

I cross checked it by doing chain rule

The answer is correct