JEE Main20209 Jan 2020Evening ShiftMathematicsSequences and SeriesActual
The number of terms common to the two A.P.’s 3 , 7 , 11 , … , 407 and 2 , 9 , 16 , … , 709 is ____________.
Correct answer
0
Step-by-step solution
Common Difference of first series = 4 Common difference of second series = 7 First common term = 23 Common difference = L . C . M 7 × 4 = 28 To find number of common terms we put Last term ≤ 407 ⇒ 23 + n - 1 × 28 ≤ 407 ⇒ n - 1 × 28 ≤ 384 ⇒ n ≤ 13.71 + 1 ⇒ n ≤ 14.71 ⇒ n = 14