A level Maths OCR question help

for this question i realised that bc it was cubic the function would be something like ax^3+bx^2+ax +c ( 2 a's bc it says they're the same in the question) but then I don't really know where to go from there.

also I realised there's no c bc it crosses (0,0)

(edited 4 months ago)

Reply 1

esha06

Original post by esha06

Reply 2

mqb2766

Original post by esha06

The third item says (2,9) is a stationary point.

So you should have enough to get the coefficients a, b. Write each part out clearly in terms of the cubic (and its derivative).

(edited 3 months ago)

Reply 3

esha06

Original post by mqb2766

The second item says the origin (0,0) lies on the curve
The third item says (2,9) is a stationary point.

So you should have enough to get the three coefficients a, b and c. Write each item out clearly in terms of the cubic (and its derivative).

i did that but idk what to do with the coordinate

also I just realised the last x should be a

(edited 4 months ago)

Reply 4

mqb2766

Original post by esha06

i did that but idk what to do with the coordinate

also I just realised the last x should be a

So you have two "points" in terms of two unknowns a, b so solve simultaneously.

Reply 5

esha06

Original post by mqb2766

So you have two "points" in terms of two unknowns a, b so solve simultaneously.

but if i substitute (0,0) into g(x) ill get get 0

Reply 6

mqb2766

Original post by esha06

but if i substitute (0,0) into g(x) ill get get 0

youve already used that point to get c=0. You are told for this point that
9 = g(2)
0 = g'(2)
so two simultaneous equations in two parameters.

Its really worth writing each point down mathematically like this.

As per a previous thread, can you try giving a more meaningful title.