Math, asked by bhideaniruddha551, 8 months ago

If S10 = 55 and S9 = 45 find a10

Answers

Answered by shashi151297
7

Step-by-step explanation:

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

S10=10/2{2a+9d}

55=5{2a+9d}

11=2a+9d----------1

S9=9/2{2a+8d}

45x2=9{2a+8d}

10=2a+8d-----------2

eqn1 - eqn2

d=1

put the value of d in eqn1

a=1

t10=1+9x1

=1+9

=10

Answered by ChitranjanMahajan
3

Given:

S10 = 55 and S9 = 45

To Find:

a10

Solution:

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

S10 = 10/2{2a+9d}

55 = 5{2a+9d}

11 = 2a + 9d                ----------(1)

S9 = 9 / 2{2a+8d}

45x2 = 9{2a+8d}

10 = 2a + 8d               -----------(2)

On subtracting (2) from (1), we get

d=1

Putting the value of d in (1) , we get

a=1

t10 = 1 + 9x1

      = 1 + 9

      = 10

Hence, a10 = 10.

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