Which term of the sequence 17, 25, 33, 41 is just greater than 90 : - Maths - Arithmetic Progressions

Question

Which term of the sequence 17, 25, 33, 41 is just greater than
90 :

Vijay Kumar Gupta · Accepted Answer

Consider  the arithmetic progression
      17, 25, 33, 41,
Here first term, a=17The common difference is    d=a2-a1     =25-17     =8Take an>90 ans use the formula an=a+n-1d      a+n-1d>90    17+n-18>90      17+8n-8>90             9+8n >90                   8n >81                     n >818                     n >10
125so the value of n is 11Find a10 and a11 a10=a+10-1d        =17+9×8        =17+72        =89and  a11=a+11-1d        =17+10×8        =17+80        =97Note that for n=10,  an<90 and for n=11,  an>90Hence the required value is 11So the 11th term is just greater than 90

Which term of the sequence 17, 25, 33, 41.... is just greater than 90.: