Check whether -150 is a term of the A.P. 11, 8, 5, 2, …

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The question is given from NCERT Book of class 10th Chapter number 5 Ex. 5.2 Q. 6. In the following question you have to find that is -150 a term of the above series or not. Give its solution briefly.

Solution:a= 11d=a_{2}−a_{1}= 8−11 = −3Let −150 be the nth term of the A.P.

For an A.P we know

a=_{n}a+(n−1)d-150 = 11+(

n-1)(-3)-150 = 11-3

n+3-164 = -3

nn= 164/3Hence,

nis not an integer it is a fraction.– 150 is not a term of the series given above.