InterviewSolution
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InterviewSolution
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In a AP GIVEN D=5,S9=75 evaluate A and A9 |
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Answer» Hm this is correct d = 5S9 = 75By applying the formulaSn = n / 2 + ( 2a + ( n - 1 ) × d75 = 9 / 2 + (2a + ( 9 - 1 ) × 575 = 9 / 2 + ( 2a + 40 )75 × 2 / 9 = 2a + 4050 / 3 = 2a + 4050 / 3 - 40 / 1 = 2aby taking LCM we will get- 70 / 3 = 2aa = - 70 / 3 × 2a = - 35 / 3.a9 = a + 8d= -35 / 3 + 8 × 5= - 35 / 3 + 40= -35 + 120 / 3= 95 / 3. |
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