Question

3rd and 4th term of an AP is 15 and 35. find the 1st term and common difference.​

Answer 1

Answer:

Step-by-step explanation:

given,

T₃=15 and T₄=35

a+2d=15 ... (i)

a+3d=35...(ii)

on solving eqn. (i)&(ii) we get

d=20

now, putting value of d in (i), we get

a+2×20=15

a=-25

Hence, first term=-25and common difference=20

Answer 2

Answer:

1st term = -25

common difference = 20

Step-by-step explanation:

3rd term = 15

4th term = 35

AP term can be written as tₙ = a + (n-1)d

a = first term; n number of term; d = common difference

t₃ = 15 = a + (3-1)d = a+2d

t₄ = 35 = a + (4-1)d = a + 3d

t₄-t₃ = (a + 3d) - (a+2d) = 35-15 = 20

d = 20

t₃ = 15 = a + 40 => a = -25

Hope it helps

Please mark as brainliest