Question

Today is my exam please help me
If 18 m n -3 in ap then find value of
M and n.

Answer 1

If 18, m, n, -3 are in ap then
common difference of two successive terms are equal

m-18=n-m

2m-n=18 ...eq1

n-m= -3-n

2n-m=-3

m-2n=3....eq2

Solve eq1 and 2

multiply eq 2 with 2 and subtract

2m-n=18
2m-4n=6
- + -
_________
3n=12

n=4

put value of n in eq1

2m-4=18

2m=22

m=11

So, value of m=11,n=4

Hope it helps you.