Learn all Concepts of Chapter 5 Class 10 (with VIDEOS). Check - Arithmetic Progressions - Class 10


Last updated at Feb. 11, 2021 by Teachoo
Transcript
Ex 5.2 ,7 Find the 31st term of an A.P. whose 11th term is 38 and the 16th term is 73 We know that an = a + (n 1) d From (1) & (2) 38 10d = 73 15d 38 73 = 15d 10d 35 = 5d ( 35)/( 5) = d 7 = d d = 7 Putting the value of d in (1) a = 38 10 d a = 38 10 7 a = 38 70 a = 32 We need to find the 31st term So, n = 31, a = 32, d = 7 We need to find an an = a + (n 1) d Putting values a31 = 32 + (31 1) 7 = 32 + 30 7 = 32 + 210 = 178 Therefore, the 31st term of AP is 178
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