form 2maths

a. x^2-49=x^2-7^2=(x-7)(x+7)
b. 36X^2-25Y^2X^2
=X^2 * (36-25Y^2)
=X^2 * [6^2 - (5Y)^2]
=X^2 * (6-5Y)(6+5Y)
c.5X^2-60X+180
=5(X^2-12X+36)
=5[X^2-2(6)(X) +6^2]
=5(X-6)^2
d.9(X-2)^2-6(x-2)+1
=[3(X-2)]^2-2(1)[3(X-2)]+1
=[3(X-2)-1]^2
=(3X-7)^2
e.(x^2+2xy+y^2)-(6x+6y)+9
=(x+y)^2-2(3)(x+y)+3^2
=(x+y-3)^2

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

36X^2-25Y^2X^2
=(6x-5xy)(6x+5xy)

5X^2-60X+180
=5(x^2-12x+36)
5(x-6)^2

9(X-2)^2-6(x-2)+1
=[3(x-2)-1]^2
=(3x-7)^2

(x^2+2xy+y^2)-(6x+6y)+9
=x^2+y^2+3^2+2xy-6x-6y
=(x+y-3)^2

2007-10-21 14:21:28 補充：
36X^2-25Y^2X^2=(6x-5xy)(6x+5xy)=x^2(6-5y)(6+5y)