Question

a3=15 s10=125 find d and a10​

Answer 1

Answer:

$d = (- 1)$

$a10 = 8$

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Answer 2

Answer:

Step-by-step explanation:

a3=a+(n-1)d

=>15=a+(3-1)d

=>15=a+2d ......... (1)

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

=>S10=10/2{2a+(10-1)d}

=>125=5(2a+9d)

=>2a+9d=125/5

=>2a+9d=25 .......... (2)

From equation (1) and (2),

a+2d=15 ....×2

2a+9d=25

2a+4d=30

---------------

2a-2a+9d-4d=25-30

=>5d=-5

=>d=-1

Put the value of d in equation (1)

a+2×-1=15

=>a=15+2

=>a=17

Now,

a10=a+(10-1)d

=>a10=17+9×(-1)

=>a10=17-9

=>a10=8