Question

what is the sum of integers from -20to 23​

Answer 1

Answer:

66 is the answer.

-20 to +20 will be cancelled. So we take numbers after 20,

21+22+23 = 66

#WMK

Answer 2

Step-by-step explanation:

-20, - 19, - 18,............23

Here a = - 20, d = 1, $t_n= 23$, $s_n=?$

$t_n= a + (n - 1)d \\ \therefore \: 23 = - 20 + (n - 1) \times 1 \\ \therefore \: 23 + 20 = (n - 1) \\ \therefore \: 43 = n - 1\\ \therefore \: 43 + 1 = n \\ \huge \red{\boxed{\therefore \: n = 44}} \\ \\ now \: \\ \because \: s_n= \frac{n}{2} \{a + t_n \} \\ \therefore \: s_{44}= \frac{44}{2} \{ - 20+ 23 \} \\ \\ \therefore \: s_{44}= 22 \times 3 \\ \\ \huge \purple{ \fbox{\therefore \: s_{44}= 66}}$