Question

The first term of an ap is -3 and the 10th term is 15 find S10

Answer 1

Answer:

S10=60

Step-by-step explanation:

SOF HERE THE QUESTION GOES AS THE FIRST TERM OF AN AP IS -3 AND THE 10 THE TERM IS 15.FIND S10

SO FIRST WE FIND d VALUE..

a=-3

a10=15

therefore, a+9d=15

-3+9d=15

9d=18

d=2

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

S10= 10/2(2[-3]+[10-1]2)

S10=5(-6+[9]2)

= 5(-6+18)

S10= 5×12

S10=60

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