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If the quadratic equation `ax^2 + 2cx + b = 0 and ax^2 + 2bx + c = 0 (b!=c)` have a common root, then `a + 4b + 4c =`A. -2B. -1C. 0D. 1 |
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Answer» Correct Answer - C Let `alpha` be the common root of the given equations. Then, `a alpha^(2) + 2 c alpha + b = 0 and, a alpha^(2) + 2 b alpha + c = 0` `2 alpha(c-b) + (b-c) = 0" "["On subtracting"]` `alpha =(1)/(2)" "[because b ne c]` Putting `alpha = 1//2 "in" a alpha^(2) + 2 c alpha + b = 0`, we get `a + 4b + 4c = 0`. |
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