The second term of an arithmetic sequence is 18 and its fourth term is 32 write its third and first terms

Dear student,
We know that nth term of an A.P. is an=a+n-1d  where, a is first termd=common difference Now, a2=a+2-1d18=a+d       --[1]also, a4=a+4-1da+3d=32     --[2]solving [1] and [2]a+d=18a+3d=32-   -    -       -2d=-14    d=7put d=7 in [1]18=a+7a=18-7a=11 To find the third term a3=a+2da3=11+2×7a3=11+14a3=25Thus the first term of an A.P is 11and  the third term of an A.P is 25
Regards

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