Question

if the sum of first four terms of AP is 40 and the sum of first 14 term of AP is 28 find the sum of first and AP ​

Answer 1

Answer:

s4=40

s14=28

4/2[2a+(3)d]

4a+6d=40.

2a+3d=20. -1

S14=28

14/2[2a+(13)d]

14a+91d=28.

2a+13d=4. -2

solving eqn 1 and 2,we get

-10d=-16

then d= -1.6

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