F.2數學題1條 (10分!!!!!!!!!)
回答 (8)
2008-01-25 2:56 am
✔ 最佳答案
(12x+4)(Ax-2)≣ 6x²+Bx+C12Ax²+4Ax-12x-6=6x²+Bx+C
A=1/2 B=4(1/2)-12 C=-6
起碼幫到你啦
2008-01-25 00:23:06 補充：
c係-8先o岩乘錯數xd
2008-01-25 00:26:08 補充：
對唔住乖錯左數=.=你跟二樓個哥哥啦,佢解釋得比較清淅同埋起碼唔似我咁計錯數
2008-01-25 3:31 am
展開(12x+4)(Ax-2)
(12x+4)(Ax-2)=12Ax²-24x+4Ax-8
=12Ax²-(24-4A)x-8
因為左面=右面
12Ax²-(24-4A)x-8 ≣ 6x²+Bx+C
所以
12Ax²=6x²
12A=6
A=1/2
-(24-4A)x=Bx
-24+4A=B <---------代A=1/2入去
-24+4(1/2)=B
-24+2=B
B=-22
所以A=1/2 B=-22 C=-8
(12x+4)(Ax-2)=12Ax²-24x+4Ax-8
=12Ax²-(24-4A)x-8
因為左面=右面
12Ax²-(24-4A)x-8 ≣ 6x²+Bx+C
所以
12Ax²=6x²
12A=6
A=1/2
-(24-4A)x=Bx
-24+4A=B <---------代A=1/2入去
-24+4(1/2)=B
-24+2=B
B=-22
所以A=1/2 B=-22 C=-8
2008-01-25 3:05 am
(12x+4)(Ax-2)≣ 6x²+Bx+C
L.H.S.=((12x+4)(Ax-2)
=12Ax²+4Ax-24x-8
=12Ax²+x(4A-24)-8
∵(12x+4)(Ax-2)≣ 6x²+Bx+C,
∴By comparing the coeffient of the like terms：12A=6
A=6/12
A=1/2〃
B=4A-24
B=4(1/2)-24
B=2-24
B=-22〃
L.H.S.=((12x+4)(Ax-2)
=12Ax²+4Ax-24x-8
=12Ax²+x(4A-24)-8
∵(12x+4)(Ax-2)≣ 6x²+Bx+C,
∴By comparing the coeffient of the like terms：12A=6
A=6/12
A=1/2〃
B=4A-24
B=4(1/2)-24
B=2-24
B=-22〃
2008-01-25 3:00 am
左方=12Ax^2-(24-4A)x-8
即12Ax^2=6x^2
12A=6
A=1/2
(24-4A)x=Bx
代A=1/2 (24-2)x=Bx
22=B
即12Ax^2=6x^2
12A=6
A=1/2
(24-4A)x=Bx
代A=1/2 (24-2)x=Bx
22=B
2008-01-25 2:58 am
(12x+4)(Ax-2) ≣ 6x²+Bx+C
L.H.S=(12x+4)(Ax-2)
12Ax²+4Ax-12x-8
12Ax²+x(4A+12)-8
R.H.S=6x²+Bx+C
by comparing like terms,
A=1/2 B=4*1/2+12
=14
L.H.S=(12x+4)(Ax-2)
12Ax²+4Ax-12x-8
12Ax²+x(4A+12)-8
R.H.S=6x²+Bx+C
by comparing like terms,
A=1/2 B=4*1/2+12
=14
參考: me
2008-01-25 2:57 am
If (12x+4)(Ax-2) ≣ 6x²+Bx+C, find A,B.
first, expand (12x+4)(Ax-2) ,
LHS=(12x+4)(Ax-2)
=12Ax²+4Ax-24x-8
=12Ax²+(2A-24)x-8
due to LHS=RHS
so, 12Ax²+(2A-24)x-8=6x²+Bx+C,
no we can find that 12A=6,2A-24=B, -8=C
so,A=1/2, B=12(1/2)-24=-18
then we can find out the answer quickly~^^
first, expand (12x+4)(Ax-2) ,
LHS=(12x+4)(Ax-2)
=12Ax²+4Ax-24x-8
=12Ax²+(2A-24)x-8
due to LHS=RHS
so, 12Ax²+(2A-24)x-8=6x²+Bx+C,
no we can find that 12A=6,2A-24=B, -8=C
so,A=1/2, B=12(1/2)-24=-18
then we can find out the answer quickly~^^
參考: myself
2008-01-25 2:56 am
(12x+4)(Ax-2)
=12Ax^2 - 24x+4Ax-8
12Ax^2 -(24+4A)x - 8 = 6x^2+Bx+C
Then, 12Ax^2 = 6x^2
12A = 6
A = 0.5
-(24+4A) = B
-(24 +2) = B
B = -26
C = -8
2008-01-24 18:58:58 補充：
Sorry, did one thing wrong. it should be -(24 - 4A) =B , so B = -22
=12Ax^2 - 24x+4Ax-8
12Ax^2 -(24+4A)x - 8 = 6x^2+Bx+C
Then, 12Ax^2 = 6x^2
12A = 6
A = 0.5
-(24+4A) = B
-(24 +2) = B
B = -26
C = -8
2008-01-24 18:58:58 補充：
Sorry, did one thing wrong. it should be -(24 - 4A) =B , so B = -22
參考: I guess
2008-01-25 2:56 am
(12x+4)(Ax-2) ≣ 6x²+Bx+C
L.H.S= 12Ax² +4Ax-24x-8
R.H.S=6x²+Bx+C
By comparing like terms, we have
12A=6
A=1/2
B=4A-24
= -22
C= -8
2008-01-24 18:57:37 補充：
與stlouisschool2002 的答法大同小異,用邊個都得
L.H.S= 12Ax² +4Ax-24x-8
R.H.S=6x²+Bx+C
By comparing like terms, we have
12A=6
A=1/2
B=4A-24
= -22
C= -8
2008-01-24 18:57:37 補充：
與stlouisschool2002 的答法大同小異,用邊個都得
參考: 剛剛學左
收錄日期: 2021-04-24 10:26:30
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