Question

what is the first term of an A.P whose third term is 440and the common difference-20?​

Answer 1

Answer:

AP: 480,460,440,420.....

Step-by-step explanation:

given:

third term($a_{3}$)= 440

common difference(d) =-20

third term($a_{3}$)=a+2d                                                                                           where a= first term and d= difference

using the formula and putting all the given values

$a_{3}$=a+2*-20

440=a-40

a=440+40

a=480

first term(a)=480

seond term($a_{2}$)= a+d

$a_{2}$=480+(-20)

$a_{2}$ =460

third term($a_{3}$)=440                  (given)

fourth term($a_{4}$)=a+3d

$a_{4}$ =480+3*-20

$a_{4}$ =480-60

$a_{4}$ =420

AP: 480,460,440,420...........