x^3-7x+6
=x^3-7x+27-21
After that, I don't know how to calculate
Please help me as soon as possible
Factorization
2007-10-24 6:59 am
回答 (4)
2007-10-24 7:35 pm
✔ 最佳答案
Do you know: a^3 + b^3 = (a+b) (a^2 - ab + b^2)then:
x^3-7x+27-21 = x^3+27-7x-21
= x^3+3^3-7x-21
= (x+3) (x^2 - 3x + 3^2) - 7(x+3)
= (x+3) (x^2 - 3x + 3^2 - 7)
= (x+3) (x^2 - 3x + 2)
= (x+3) (x-2) (x -1)
參考: myself
2007-10-24 7:22 am
=x^3+27=7x-21
=(x+3)(x^2-3x+9)- 7x-21
=(x+3) (x^2-3x+9)-7(x+3)
=(x+3)( x^2-3x+9-7)
=(x+3)( x^2-3x+2)
=(x+3)(x +2)( x-1)
=(x+3)(x^2-3x+9)- 7x-21
=(x+3) (x^2-3x+9)-7(x+3)
=(x+3)( x^2-3x+9-7)
=(x+3)( x^2-3x+2)
=(x+3)(x +2)( x-1)
參考: me
2007-10-24 7:19 am
x^3-7x+6
= x^3 + x^2 - 6x - x^2 - x + 6
= x^3 + x^2 - 6x - (x^2 + x - 6)
= (x - 1)(x^2 + x - 6)
= (x - 1)(x - 2)(x + 3)
(If you have learned factor theorem, then you can try to sub. x = 1 or 2 or -3 to find out the factor of the expression.)
= x^3 + x^2 - 6x - x^2 - x + 6
= x^3 + x^2 - 6x - (x^2 + x - 6)
= (x - 1)(x^2 + x - 6)
= (x - 1)(x - 2)(x + 3)
(If you have learned factor theorem, then you can try to sub. x = 1 or 2 or -3 to find out the factor of the expression.)
2007-10-24 7:04 am
你計錯喇..寫條式出黎等我睇下喇..
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