AQA Core 4 Jan 2013 Q4

AQA Core 4 January 2013 exam paper on implicit differentiation, equations of tangents and parametric equations.

[KhanIOM]

Thanks for these videos- sooo helpful when I can't work out the answer despite seeing the mark scheme :)

[jgindahouse]

oh yes I can see what you've done now, thanks for the feedback! I'm sitting Core 4 tomorrow :(

[mathedup]

We have done the same thing, I just cancelled out the "t" earlier in my working out.. Your way would be fine too..

[jgindahouse]

for 4b, when you expanded the brackets and formed the two quadratics, you then ignored the brackets when simplifying. When I did it I got the t^2 terms cancelling, the 4/t^2 terms cancelling and I was left with 8t/t which cancels to 8 hence proving the answer is correct. Have I done something wrong or are both methods correct?

[hamzaabuelmagd]

How do you deduce the gradient of -p/q for tangent at (p, -q)?