1.

Find the 31th Ferm of an BAP whose 11th term is 38and 10th is 73.

Answer»

11th=38; 16th=73; 11th= a + 10d =38, 16th=a + 15d=73/5d=35; 5d=35; d = 35/5=7; a=38-10d=38-10(7)=38-70=-32; a=32; n=31,;d=7

it is correct answer

a= 32 n= 31 d = 7 is the correct answer of the given

let 1st term = a , diff = d11 th term = 38a+10d= 38a+15d= 73by subtracting -5d= -35d= 35/5=7a+10d= 38a= 38-10×7 = 38-70= -32so 31 th term,= a+(n-1)d = -32+(31-1)×5 = -32+150 = 118

We know that,an=a+(n-1) dGiven :11 th term is 38a11=a+(11-1)d38=a+10d38-10d=aa=38-10d...(1)16 th term is 73a16=a+(16-1)d73=a+15d73-15d=aa=73-15d...(2)from (1) and (2)38-10d=73-15d38-73=-15d-10d-35= -5d-35÷-5=dd= 7Substitute value of d in equation (1)a=38-10(7)a=38-70a=-32we need to find 31st term,n=31,a=-32,d=7an=a+(n-1)da31=-32+(31-1)7 =-32+30×7 =-32+210 =178Therefore 31st term of AP is 178


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