Let , be roots of x2 + 2x - 8 = 0. If Un = n + n, then U10 + 2 U92U8 is equal to .
Answer
4
Solution
is a root: 2 + 2 = 8; multiply by 8: 10 + 2 9 = 8 8
Similarly 10 + 2 9 = 8 8
Add: U10 + 2 U9 = 8U8
U10 + 2 U92U8 = 82 = 4
Answer: 4
Let , be roots of x2 + 2x - 8 = 0. If Un = n + n, then U10 + 2 U92U8 is equal to .
4
is a root: 2 + 2 = 8; multiply by 8: 10 + 2 9 = 8 8
Similarly 10 + 2 9 = 8 8
Add: U10 + 2 U9 = 8U8
U10 + 2 U92U8 = 82 = 4
Answer: 4
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