Question 9 Exercise 7.2

Solutions of Question 9 of Exercise 7.2 of Unit 07: Permutation, Combination and Probablity. This is unit of A Textbook of Mathematics for Grade XI is published by Khyber Pakhtunkhwa Textbook Board (KPTB or KPTBB) Peshawar, Pakistan.

Q9 Find numericalty greatest term in the expansion (xy)="(xy)=" when x=12x=12 and y4y4. Solution: When we put x=12x=12, then the give becounes (xy=20(12y)20=122n(1y12)31

Now we theck (n+1)x1+|x| for (112)2 Here n=20 and |x=|y12|=13 for y=4 (n+1);41+|x|=(20+1)131+13 734=214=5+0.25=p+F

Thus 5+1=6tt of the 12201(1y12)20 is greatest i.c. T6=12202(0!(205)!5!(y12)5

For y=4, it becomes T6=122020!15!5!(13)2=T6122011)520!15!5!135=T6=1220155041243=24460335÷54230.438655932 K.

Ilenec this term Tκ is numerically greates writlen abeve