An important question from ML Pulication of Class 10 from Arithmetic Progression Chapter.
If the common difference of an AP is -3 and the 18th term is -5. Find its first term.
Class 10 ML Publication, chapter 9, Arithmetic Progression
If the common difference of an AP is -3 and the 18th term is -5. Find its first term.
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Tn​=a+(n−1)d
T18​=a+(18−1)d
−5=a+(18−1)(−3)
−5=a+(17)(−3)
−5=a−51
a=51−5
a=46​
Therefore, first term a=46