Q1.if 20th term and 30th term of Arthematic progression are 121 and 181 respectively find the 40th term of Arthematic progression
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Step-by-step explanation:
✬ 40th Term = 241 ✬
Step-by-step explanation:
Given:
20th and 30th term of an AP is 121 and 181 respectively.
To Find:
What is the 40th term of AP ?
Solution: As we know that an AP series is given by
★ a + (n – 1)d ★
a = first term
n = number of terms
d = common difference
A/q
20th term is 121.
➙ a + (20 – 1)d = 121
➙ a + 19d = 121
➙ a = 121 – 19dㅤㅤㅤㅤㅤeqⁿ i
Now ,
30th term is 181
➙ a + (30 – 1)d = 181
➙ a + 29d = 181
➙ 121 – 19d + 29d = 181 ㅤㅤㅤfrom eqⁿ i
➙ 10d = 181 – 121
➙ d = 60/10 = 6
So the common difference of AP is 6. Now putting the value of d in eqⁿ 1.
➮ a = 121 – 19 × 6
➮ a = 121 – 114
➮ a = 7
So the first term of AP is 7.
∴ 40th term will be
⟹ a + (40 – 1)d
⟹ 7 + 39 × 6
⟹ 7 + 234
⟹ 241
Hence, the 40th term of AP will be 241.
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