Question

which term of AP: 24,21,18......is -78?​

Answer 1

$\underline{ \underline { \huge \red{\mathbb{ANSWER}}}}$

here,

• a = 24
• d = -3
• an = -78

an = a + (n - 1)d

➪ -78 = 24 + (n - 1)-3

➪ -78 = 24 -3n + 3

➪ 3n = 24 + 3 + 78

➪ 3n = 105

➪ n = 105/3

➪ n = 35

so, -78 is 35th term of AP