Would this get any marks?

leoishush

I also did 4(2n+1)/(2n) on the other side

(edited 1 year ago)

Screenshot 2022-06-16 9.10.23 PM.png41.0KB

Reply 1

mqb2766

Original post by val7322

I also did 4(2n+1)/(2n) on the other side

Not sure it would, you seem to be starting from what youre trying to prove, rather than deducing the inequality. Id guess the key thing would be to start trying to get the method right. A couple of things Id probably do to get started for a problem like this would be
1) recognise that as its an (quadratic) inequality, the starting point may be something like ()^2 >= 0
2) In rough working, work back a couple of steps from the answer, so as its a fraction, multiply through by the common divisor ab (its positive) to get
4a^2 + b^2 >= 4ab
or
4a^2 - 4ab + b^2 >= 0
Hopefully youd now recognize that the left hand side is (2a - b)^2 and so we now know what to do.

An alternative is to spot that you could write z=a/b so youd get a quadratic in z in a similar fashion.