Question

a3=15 or s10=125 given d or a10

Answer 1

Answer:

d= -1

a10 = 8

Explanation:

$\frac{n}{2} (2a + (n - 1)d) = s$

Sum of n terms of A.P

• S(10) = (10/2)(2a+(10-1)d
• 125 = 5(2a+9d)
• 25= 2a+9d---------eq.1

a(n) = a+(n-1)d. ( nth term in A.P )

• a3 = a +2d
• 15 = a+2d------------ eq.2

From equation 1 and 2

a= 17 and d = -1

so a(10) = a+ 9d

= 17+9(-1)

= 8