F4 Nature of roots
2011-10-16 6:54 am
Q2 Given that r is a root of the quadratic equationx^2-3x-5=0, find the valueof r^5-3r^4-5r^3+2r^-6r
回答 (1)
2011-10-16 7:06 am
✔ 最佳答案
Since r is a root of the quadratic equation x^2 - 3x - 5 = 0,i.e. r^2 - 3r - 5 = 0
r^5-3r^4-5r^3+2r^2-6r
= r^3 (r^2 - 3r - 5) + 2r^2 - 6r - 10 + 10
= r^3 (r^2 - 3r - 5) + 2(r^2 - 3r - 5) + 10
= 0 + 0 + 10
= 10
參考: Hope the solution can help you^^”
收錄日期: 2021-04-13 18:18:18
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111015000051KK01118