Question

1. Find the sum of the following APs:
(1) 2,7,12,..., to 10 terms.
ii) 0.6, 1.7,2.8,..., to 100 terms.​

Answer 1

Answer:

1.1 245

1.2 5505

Step-by-step explanation:

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

1.1 a=2, d=5

10/2(2(2)+(10-1)5)

5*(4+45)

5*49

245

1.2 a=0.6, d=1.1

100/2(2(0.6)+(100-1)1.1)

50*(1.2+108.9)

50*110.1

5505

Answer 2

${\boxed{\blue{\bf{Answer \: 01}}}}\\ using \: formula \\ {\boxed{\green{\bf{sn = n \div 2(2a + (n - 1)d)}}}} \\ sn = \frac{10}{2} {({2(2) + (10 - 1)(5)})} \\ sn = 5(4 + 45) \\ sn = 5(49) \\ sn = 245 \\ \\ {\boxed{\blue{\bf{Answer \: 02}}}} \\using \: formula \\ {\boxed{\green{\bf{sn = n \div 2(2a + (n - 1)d)}}}} \\ sn = \frac{100}{2} {({2(0.6) + (100 - 1)(1.1)})} \\ sn = 5o(1.2 + 108.9) \\ sn = 50(110.1) \\ sn = 5505$