I have already done question 3A,
so this is my attempt so far at 3B
i substituted 4x+k in to y^2
then I got (4x+k)^2=25
then 4x+k=+-5, after that i made k the subject which gave me k=+-5-4x
beyond this point i have no idea what i was doing so i attempted to swap in the value of x=+-3 into the equation but doing so gave me a range of different values, please help thanks
P.S if you know any good revision sites for these questions or general conic section please include it in your answer, thanks