Question

Find the 20th term of the A.P. -40, -15, 10,…​

Answer 1

Answer:

an = a + (n-1) d

= -40 + (20-1) 25

= -40 + 475

a20 = 435

Answer 2

$\pink{given : } \: \: \: \: \: \: \: \: \: \\ \\ -40, -15, 10,… \\ \\ \blue{to \: \: \: find : } \\ \\ t20 \\ \\ \green{solution : } \\ \\ \red{tn = a + (n - 1)d} \\ \\ now \\ \\ -40, -15, 10,… \\ \\ a = - 40 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ d \: \: = - 15 - ( - 40) \ \\ = - 15 + 40 \: \: \: \\ = 25 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \pink{t20 = a + (20 - 1)d} \\ \\ t20 = - 40 + 19 \times 20 \\ \\ t20 = - 40 + 475 \: \: \: \: \: \: \: \: \: \\ \\ \blue{t20 = 435} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$

HOPE IT HELPS TO U