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19. For what value of k does (k-12) x + 2(k-12) x + 2 0 have equal roots? |
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Answer» Equal roots exist if DIscriminant = 0=> [2(k-12)]^2 - 4(k-12)(2) = 0=> 4*( k-12)^2 - 8( k -12) = 0=> 4k^2 + 576 - 96k - 8k + 96 = 0=> 4k^2 - 104k + 672 = 0=> k^2 - 26k + 168 = 0=> k^2 - 12k - 14k + 168 = 0=> k(k-12) - 14(k - 12) = 0=> k = 12, 14 |
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