Question

the sum of first 5 terms and 9th terms of an ap is 72 and sum of the first 7th and 12th is 97 find the ap​

Answer 1

Answer:

a5 +a9=72

a+4d+a+8d=72

2a+12d=72............eq1

and

a7+a12=97

a+6d+a+11d=97

2a+17d=97.............eq2

subtracting eq1 from eq2

2a+17d=97

2a+12d=72

(-) (-) (-)

__________

5d=25

d=25/5

d=5

put d=5 in eq1

2a+12(5)=72

2a+60 =72

2a=72-60

a=12/2

a=6