Question

Given a3=15,s10=125, find d and a10



please dhang sai ans doo please kal exam hai please full explanation please ​

Answer 1

Answer:

Let a is the first term and d is the common difference of the AP

Given, a3 = 15

=> a + 2d = 15

=> a = 15 - 2d ..............1

Again given

S10 = 125

=> (10/2)*{2a + (10 - 1)d} = 125

=> 5(2a + 9d) = 125

=> 2a + 9d = 125/5

=> 2a + 9d = 25

From equation 1, we get

2(15 - 2d) + 9d = 25

=> 30 - 4d + 9d = 25

=> 30 + 5d = 25

=> 5d = 25 - 30

=> 5d = -5

=> d = -5/5

=> d = -1

From equation 1,

a = 15 - 2(-1)

=> a = 15 + 2

=> a = 17

Now, a10 = a + 9d

=> a10 = 17 + 9*(-1)

=> a10 = 17 - 9

=> a10 = 8

Answer 2

Answer:

Hey,

The answer of ur question is:

Step-by-step explanation:

Hope it helps...

Have a nice day.☀☀✌

all the best for ur exam and plz wish for me also because i m also in 10th.....