Question

If the nth term of an
a.p. is given by a n n = 5 3 − , then the sum of first 10 terms if

Answer 1

The sum of first 10 terms is 245.

Step-by-step explanation:

Consider the provided information.

The nth term is given by $a_n=5n-3$

Substitute n=1 in above expression.

$a_1=5(1)-3\\a_1=2$

Substitute n = 2 in above expression.

$a_2=5(2)-3\\a_2=7$

Thus, the first term of A.P is 2 and second term is 7.

Therefore common difference is d=7-2=5

The formula to calculate the sum of A.P is: $S_n=\frac{n}{2}(2a+(n-1)d)$

Substitute a=2, d=5 and n=10 in above formula.

$S_{10}=\frac{10}{2}(2(2)+(10-1)5)$

$S_{10}=5(4+(9)5)$

$S_{10}=5(4+45)$

$S_{10}=5(49)$

$S_{10}=245$

Hence, the sum of first 10 terms is 245.

#Learn more

If the nth term of an A.P is given by 5n-3 then find 5hr sum of first 10 terms

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Answer 2

Answer:

n=1, 10          a=2        l=47                            

Step-by-step explanation:

S10= 10/2(2+47)

      =5 (49)

      =  245