some

[pine orchid]

This was the best question ever

n!/r!(n-r)! = nCr

n!/2!(n-2)! * 3^n/9 * (ax)^2 = 4860x^2
n!/(n-2)! * 3^n/18 * a^2 = 4860

n! = n(n-1)(n-2)!
cancel (n-2)!
n(n-1)(3^n)(a^2) = 4860*18

n(n-1)(3^n)(a^2) = 87480

[bleak comet]

Bruh I’m confused

Can u write it out on paper

[pine orchid]

yes sure

[bleak comet]

Ahh I’m getting it a bit motr

What formula did u use to get the thing

[pine orchid]

ncr formula is in the aqa booklet thingy

then just used the 4860 from the lil bit of info from above the question