The following shows a question of a mathematics quiz:rewrite 3x²+■x-8 as (3x+m)(x+n),where m and n are integers.
However, due to a printing error, the coefficient of x is covered by an ink drop and cannot be seen. Write down the possible coefficients of x.explain your answer.
求救.what are the possible coefficients of x??????
回答 (3)
2017-07-26 5:00 pm
✔ 最佳答案
Sol3x^2+ax-8=(3x+m)(x+n)
3x^2+ax-8=3x^2+(m+3n)x+mn
a=m+3n，mn=-8
(1) m=1
n=－8
a=1－24=－23
(2) m=2
n=－4
a=2－12=－10
(3) m=4
n=－2
a=4－6=－2
(4) m=8
n=－1
a=8－3=5
(5) m=－1
n=8
a=－1+24=23
(6) m=－2
n=4
a=－2+12=10
(7) m=-4
n=2
a=－4+6=2
(8) m=－8
n=1
a=－8+3=－5
2017-07-31 8:58 am
可能的組合(-8,1)(-4,2)(-2,4)(-1,8)(1,-8)(2,-4)(4,-2)(8,-1), so■= -7,-2,2,7
2017-07-26 5:23 pm
M,n are factors of 8 with mn=-8
let b = Coefficient of x
b = m+3n
Possible (m,n,b) : (1,-8,-23),(2,-4,-10),(4,-2,-2),(8,-1,5),(-1,8,23),(-2,4,10),(-4,2,2),(-8,1,-5)
let b = Coefficient of x
b = m+3n
Possible (m,n,b) : (1,-8,-23),(2,-4,-10),(4,-2,-2),(8,-1,5),(-1,8,23),(-2,4,10),(-4,2,2),(-8,1,-5)
收錄日期: 2021-04-24 00:39:09
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170726082509AALqNxA