10分6題題數(因式分解)

16.b^2-49
= (b+7)(b-7)
17.81-c^2
= (9+c)(9-c)
18.100-d^2
= (10+d)(10-d)
19.h^2-16k^2
=(h+4k)(h-4k)
20.m^2-36n^2
=(m-6n)(m+6n)
21.9p^2-64q^2
= (3p+8q)(3p-8q)

2010-09-18 01:24:29 補充：
以上各題都係用緊平方差條式...
x^2 - y^2 = (x+y)(x-y)
呢條式係中學數學好多時會用到...
一定要記實

Remember : a^2 - b^2 = ( a + b ) ( a - b )

b^2-49
=(b+7)(b-7)

81-c^2
=(9+c)(9-c)

100-d^2
=(10+d)(10-d)

h^2-16k^2
=(h+4k)(h-4k)

m^2-36n^2
=(m+6n)(m-6n)

9p^2-64q^2
=(3p+8q)(3p-8q)