(i) Here, first term a₁ = 10 and common difference, d = 10

Hence,

2^nd term a₂ = a₁ + d

= 10 + 10

= 20

3^rd term a₃ = a₁ + 2d

= 10 + 2 x 10

= 30

4^th term a₄ = a₁ + 3d

= 10 + 30

= 40

Therefore,

first four terms of the AP are:

10, 20, 30, 40, ……

(ii) Here,

First term a = -2 and Common difference = 0

Therefore, first four terms of the given AP are:

a₁ = - 2, a₂ = - 2, a₃ = - 2 and a₄ = - 2

(iii) Here, first term a₁ = 4 and common difference d = - 3

We know that a_n = a + (n – 1)d, where n = number of terms

Thus, second term a₂ = a + (2 – 1)d

a₂ = 4 + (2-1)×(-3)

= 4 - 3 = 1

3^rd term a₃ = a + (3 – 1)d

= 4 + (3-1) × (-3)

= 4 - 6

= -2

4^th term a₄ = a + (4-1)d

= 4 + (4 - 1) ×( -3)

= 4 - 9 = -5

Therefore,

First four terms of given AP are:

4, 1, - 2, - 5

(iv) We have,

1^st term = - 1 and d = 1/2

Hence,

2^nd term a₂ = a₁ + d

= -1 + 1/2

= - 1/2

3^rdterm a₃ = a₁ + 2d

= -1 + 2 * 1/2

= 0

4^th term a₄ = a₁ + 3d

= -1 + 3 * 1/2

= 1/2

Therefore,

The four terms of A.P. are -1, - 1/2, 0, 1/2

(v) We have

1^st term = - 1.25 and d = - 0.25

2^nd term a₂ = a + d

= -1.25 - 0.25

= -1.5

3^rd term a₃ = a + 2d

= -1.25 + 2 × (-0.25)

= -1.25 - 0.5

= -1.75

4^th term a₄ = a + 3d

= 1.25 + 3 × (-0.25)

= -2.25

Therefore, first four terms of the A.P. are: 1.25, -1.5, -1.75 and – 2.25