an important question from the book -ML aggarwal( avichal publication)class 10th , chapter9, arithmetic progression……..
This type of question has been asked in paper. so please solve it in detail.Find the indicated terms in each of the following arithmetic progression: -4,-7, -10, -13….a25, an.
Rajan@2021Guru
Find the indicated terms in each of the following arithmetic progression: -4,-7, -10, -13….a25, an.
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From the question,
The first term a=−4
Then, difference d=−7−(−4)=−7+4=−3−10−(−7)=−10+7=−3−13−(−10)=−13+10=−3
Therefore, common difference d=−3
From the formula, an=a+(n−1)d
S0,a25=a+(25−1)d=−4+(25−1)(−3)=−4+(24)−3=−4−72=−76
Therefore, a25=−76
Now, an=a+(n−1)d
an=−4+(n−1)−3=−4−3n+3=−1−3n