Question

The 9th. term of an A.P es equale
to Seven times the 2nd and 12th term exfee
exceeds five times the third term by 2 find a and d.​

Answer 1

Answer:

a= 1 d=6

Step-by-step explanation:

a+8d = 7(a+d)

a+8d = 7a +7d

6a = d

5(a+2d) +2 = a+11d

5a +10d +2 = a +11d

4a + 2 = d

so 4a + 2 = 6a

2a = 2

a= 1

d=6a

d= 6

Answer 2

Answer:

a = 1

d = 6

Step-by-step explanation:

let the first term be a and common difference be d

9th term = 7 * (2nd term)

a+8d = 7(a+d)

=> a+8d = 7a+7d

=> d = 6a ...... (1)

12th term = 5 * (3rd term) + 2

=> a+11d = 5(a+2d) +2

=> a+11d = 5a+10d+2

=> d = 4a+2 .... (2)

subtracting (2) from (1)

6a-4a-2 = d-d = 0

=> 2a-2 = 0

=> a = 1

d = 6a = 6

hope it helps : )