An important question from ML Agarwal (avichal publication) of class10 Find the 20th term of the AP whose 7th term is 24 less than its 11th term and first term is 12
ML Publication Class 10, Arithmetic Progression Chapter 9, question no.13
Rajan@2021Guru
Find the 20th term of the AP whose 7th term is 24 less than its 11th term and first term is 12
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Given ,
First term =a=12
Let the common difference be d
and we know 7th term a7=a+6d
and 11th term a11=a+10d
According to question ,
a11−a7=24
a+10d−(a+6d)=24
a+10d−a−6d=24
d=6
We know that,
20th term =a20=a+19d=12+19(6)
=12+114
=126
So , the 20th term of AP is 126.