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I. SHORT ANSWER TYPE QUESTIONS 25\CBSE DEDetermine the 15th term of the AP.22. Find the sum of all the natural numbers less than 100 which are divisible by21. The 6th term of an Arithmetic Progression (AP) is - 10 and its 10th term is - |
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Answer» -step explanation:A15 = a+ (N-1)da = first TERM ,n=number of terms, d=commondifference 2.first term divisible by 2 =2second term divisible by 2=4third term divisible by 2 = 6last term divisible by 2 less than 100 = 98AP formed = 2,4,6,8,...............,98an = 98 , a=2, d=2, n=?an = a+ (n-1)d98=2+(n-1)298-2=(n-1)296 = (n-1) 296/2 = n-148 =n-148+1 =n49 = NSUM of natural number less than 100 divisible by 2 =Sn = n/2 [a+ l]l means last term Sn = 49/2 [2 + 98]Sn = 49/2*100Sn = 49*50Sn = 2450 |
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