Question

Find the sum of 5 terms of 1.2 + 2.3 + 3.4 + ........​

Answer 1

Answer:

17

Step-by-step explanation:

1.2+2.3+3.4+4.5+5.6=17

Answer 2

Step-by-step explanation:

$a \: = 1.2 \: \: \: \: \: \: \: \: \: d \: = 1.1 \\ s5 = \frac{5}{2} \times (2 \times (1.2) + (5 - 1) \times 1.1) \\ s5 = \frac{5}{2} \times (2.4 + 4.4) \\ s5 = \frac{5}{2} \times 6.8 \\ s5 = 5 \times 3.4 \\ s5 = 17.0$

therefore the answer is 17