determine a factor
回答 (3)
2010-06-28 7:54 pm
✔ 最佳答案
28x2+5xy-12y2
=(7x-4y)(4x+3y)
2010-06-28 22:39:31 補充：
28x²+5xy-12y²
=28x²+21xy-16xy-12y²
=7x(4x+3y)-4y(4x+3y)
=(7x-4y)(4x+3y)
另外,可用十字相乘法,請參考意見。
2010-06-29 4:28 am
其實用十字相乘法就可以...
7x -4y
4x 3y
_________
21xy-16xy=5xy
7x -4y
4x 3y
_________
21xy-16xy=5xy
2010-06-29 12:33 am
Let f(x,y)= 28x^2+5xy-12y^2
Put x=4y/7, we have f(4y/7,y)=0
so x=4y/7 is a factor.
Note: it is the more general theorem of reminder theorem that we learn in Form 4.
Simon Yau
Put x=4y/7, we have f(4y/7,y)=0
so x=4y/7 is a factor.
Note: it is the more general theorem of reminder theorem that we learn in Form 4.
Simon Yau
參考: Simon Yau
收錄日期: 2021-04-13 17:20:08
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