Tricky Binomial Question (1 Viewer)

[BigBear_25]

This question is from Maths in focus Ex 11.2 question 9.

here is the question: The expansion (1+ax)^n is given by
1-24x+252x^2-... Find values for a and n.

Thankyou in advanced ive been stuck on this question for about 3 days
and the teachers a bum, he just started to work on it 2day and he didn't
even finish the question.

And thankyou again

 

[Mc_Meaney]

rediculous question.

 

[modezero]

This question is from Maths in focus Ex 11.2 question 9.

here is the question: The expansion (1+ax)^n is given by
1-24x+252x^2-... Find values for a and n.

Thankyou in advanced ive been stuck on this question for about 3 days
and the teachers a bum, he just started to work on it 2day and he didn't
even finish the question.

And thankyou again

(1+ax)^n=1-24x+252x^2-....
equating coefficients:
a.(nC1)=an=-24
a^2.(nC2)=a^2.n.(n-1)/2=252

so (an)^2=576
and a^2.(n^2-n)=504

subtracting: a^2.n=72
dividing: n=8
substituting: a=3 or -3
but coefficient is -24
thus a=-3