Question

Help a Little bit..i have board exam today​

Answer 1

3.)D)Sn = n/2(a +l)

4.) S15 = 15/2(1 + 29)

= 15/2 × (30)

= 15/1 × 15 = 15×15 = 225

=> A)225

l = an = a + (n-1)d