Question

what is the sum of the first 20 term of a.p if a=4 t20= 36​

Answer 1

Step-by-step explanation:

Here a ( n ) = a + ( n - 1 ) d = last term = a ( 20 ) Sum = 20/2 ( 4 + 36 ) = 10 ( 40 ) = 400. Sum of the first 20 terms is 400 .

Answer 2

Given :

First term (a) = 4

Number of terms (n) = 20

Last term (l) = 36

To find:

Sum of first 20 terms.

Solution:

We have,

The last term is 36 and first term is 4.

We also know that the sum of n terms in an A.P. is given by

$S_{n} =\frac{n}{2}(a+l)$

Substituting the given values in the equation, we get

$S_{n} = \frac{20}{2}(4+36) \\S_{n} = 400$

Final answer:

Hence, the sum of first 20 terms of the A.P. is 400.