If 4x^2 - 8x + 7 = 4( x + a )^2 +b
Find the values of a and b.
利用計算4x^2 - 8x + 7 求得4( x + a )^2 +b
A.Math
2007-10-11 6:29 am
回答 (4)
2007-10-11 6:37 am
✔ 最佳答案
since: 4x^2 - 8x + 7 =4( x + a )^2 +b 4x^2 - 8x + 7
= 4(x^2-2x)+7
=4(x-1)^2-4+7
=4(x-1)^2+3
so, a=-1 and b=3
2007-10-11 22:28:42 補充：
下面的那位,係1*4, 唔係4*4喎
2007-10-16 5:14 am
2007-10-11 5:05 pm
4x^2-8x+7
=4(x^2-2x)+7
=4(x^2-2x+1^2-1^2)+7
=4[(x-1)^2-1]+7
=4(x-1)^2-4+7
=4(x-1)^2+3
so, a=-1 and b=3
=4(x^2-2x)+7
=4(x^2-2x+1^2-1^2)+7
=4[(x-1)^2-1]+7
=4(x-1)^2-4+7
=4(x-1)^2+3
so, a=-1 and b=3
2007-10-11 7:42 am
4x^2 - 8x + 7 = 4( x + a )^2 +b
LHS: 4x^2 - 8x + 7
-----= 4(x^2-2x)+7
-----= 4(x-1)^2-16+7
-----= 4(x-1)^2- 9
so, a=-1 and b=9
so 4(x-1)^2- 9
(上面那個人回答錯了,要x4)
LHS: 4x^2 - 8x + 7
-----= 4(x^2-2x)+7
-----= 4(x-1)^2-16+7
-----= 4(x-1)^2- 9
so, a=-1 and b=9
so 4(x-1)^2- 9
(上面那個人回答錯了,要x4)
參考: myself
收錄日期: 2021-04-13 13:51:43
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