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In an A.P, sum of four consecutive term is 28 and their sum of their squares is 276. find the four number. |
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Answer» Let the numbers be: a - 3d, a - d, a + d, a + 3d a - 3d + a - d + a + d + a + 3d = 32 4a = 32 \(\therefore\) a = 8 (a - 3d)2 + (a - d)2 + (a + d)2 + (a + 3d)2 = 276 4a2 + 20d2 = 276 20d2 = 276 - 4(8)2 = 20 \(\therefore\) d = 1 Therefore the 4 numbers are: a - 3d, a - d, a + d, a + 3d = 8 - 3, 8 - 1, 8 + 1, 8 + 3 = {5, 7, 9, 11 } |
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