Question

how is intelligent they will give answer.​

Answer 1

Answer:

21) a=5,d= 4

Sn = n/2[ 2a+(n-1)d]

= 12/2[ 10 + 11 (4)]

= 6[ 10+44]

= 6 [54]

= 324

22) a=1,d=t2-t1= 3-1=2,tn=149

tn= a + (n-1)d

149= 1 + (n-1) 2

149 = 1+2n-2

149= 2n-1

150= 2n

n= 150/2= 75

Answer 2

Answer:

Sn = n / 2 { (2a + ( n - 1 ) d }

points given in the Ques are

• a is given = 5
• d is given = 4
• n is given = 12
• Sn. = ?

so now put these values in the formula

Sn = n/2 { 2a + ( n - 1 ) d

Sn = 12 / 2 { 2× 5 + ( 12 - 1 ) 4

Sn = 6 { 10 + ( 11 ) 4

Sn = 6 (10 + ( 11 × 4 )

Sn = 6 ( 10 + 44 )

Sn = 6 × 54

Sn = 324

2) points given in the que are =

• a is given = 1
• tn is given = 149

difference = a1 - a

a1 = 3

a = 1

difference = 3 - 1

difference = 2

tn = a + ( n - 1 ) d

tn = 1 + ( n - 1 ) 2

149 = 1 + 2n - 2

149 = 2n - 1

149 + 1 = 2n

150 = 2n

n = 150 / 2

n = 75

hopes it will help