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`a, b, c, in R, a ne 0` and the quadratic equation `ax^(2) + bx + c = 0` has no real roots, then which one of the following is not true?A. `a + b + c gt 0`B. `a(a+b+c)gt 0`C. `ac(a+b+c)gt 0`D. `c(a+b+c)gt 0` |
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Answer» Correct Answer - A Let `f(x) = ax^(2) + bx + c`. It is given that f(x) = 0 has no real roots. So, either `f(x) gt 0` for all x `in` R or f(x) `lt` 0 fir all x `in` R i.e. f(x) has same sign for all values of x. `therefore" "f(0) f(1) gt 0 rArr c(a+b+c) gt 0` and, `a f(1) gt 0 rArr a(a+b+c) gt 0`. Also, ac `gt` 0. `therefore" "ac f(1) gt 0 rArr ac (a+b+c) gt 0` |
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