Factorisation

因為有小數...我覺得中間打出黎有少少亂= =
所以我設 b = 1.5
50-8(a+b)²
=50-8(a²+2ab+b²)　　＜－ (a±b)²=a²±2ab+b²
=50-8a²-16ab-8b²
代回b=1.5
=50-8a²-16a(1.5)-8(1.5)²
=50-8a²-24a-18
=-8a²-24a+32
=8(-a²-3a+4)

-a　　 1
　＼／
　／＼
a　　　4
____________
1a+(-4a)=-3a

所以,8(-a²-3a+4)
=8(-a+1)(a+4)

50-8(a^2+2.25)
=50-8a^2-18
=32-8a^2
=8(4-a^2)

2008-07-29 12:03:45 補充：
=8(2^2-a^2)
=8(2-a)(2+a)

2008-07-29 12:10:08 補充：
解釋
1) =32-8a^2---------------(take the common factor=8)
=8(4-a^2)
2) =(4-a^2)-------------(identity)
=(2-a)(2+a)

2008-07-29 12:11:26 補充：
=8*2(-a)(a)
=16*-a^2
=-16a^2

2008-07-29 12:14:10 補充：
I hope I can help you because my maths is 8/205