Root-Coefficent Relationships(5)
2007-11-11 9:16 pm
Given that x2-12x+k=0 has roots a and a2, find the value of a, then find the value of k.
回答 (1)
2007-11-11 9:23 pm
✔ 最佳答案
Sum of roots = a+a^2 = 12a^2 + a - 12 = 0
(a-3)(a+4) = 0
a = 3 or -4
When a = 3, 3^2 - 12(3) + k = 0
9 - 36 + k = 0
k = 27
When a = -4, (-4)^2 - 12(-4) + k = 0
16+48 + k = 0
k = -64
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