Question

ou find the 21 term of the Ap 7, 11, 15​

Answer 1

Answer:

to find the nth term the formula is

Tn = t1 + ( n-1 ) × d

t21 = 7 + (21 - 1 ) × 4

t21 = 7 + (20) × 4

t21 = 7 + 80

t21 = 87

t21 = 87

Answer 2

Correct Question: Find the 21st term of the AP: 7,11,15

In the given AP,

⇒a = First term = 7

⇒d = Common difference

⇒d = Second term - First term

⇒d = 11-7

⇒d = 4

We need to find 21st term of the AP.

We know that:

⇒nth term = a+(n-1)d

⇒21st term = a+(21-1)d

⇒21st term = a+20d

⇒21st term = 7+20×4

⇒21st term = 7+80

⇒21st term = 87

Hence, the 21st term of the AP is 87.

Know more:

⇒An Arithmetic Progression is usually in the form of:

a,(a+d),(a+2d),(a+3d)...,(a+nd)