6.設化簡(3+根號3+根號5)(3+根號3-根號5) 7.多項式x^5-9x^4+10x^3-18x^2+20x-72除以x-8之餘視為何? 10.解方程式2x^3+7x^2+2x-3=0?

2017-05-04 7:25 pm

回答 (1)

2017-05-04 8:18 pm
✔ 最佳答案
6
Sol
(3+√3+√5)(3+√3-√5)
=(3+√3)^2-5
=12+6√3-5
=7+6√3
7
Sol
1 -9 10 -18  20 -72| 
   8 -8  16 -16  32|8
─────────────────────
1 -1  2  -2   4 |-40
餘式=-40
10
Sol
2x^3+7x^2+2x-3
=(2x^3+2x^2)+(5x^2+5x)+(-3x-3)
=2x^2(x+1)+5x(x+1)-3(x+1)
=(2x^2+5x--3)(x+1)
==(2x-1)(x+3)(x+1)


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