36a²-64c²=
1-a⁴c²=
-25c²+9a²=

(a²-b²)=(a-b)(a+b)

36a²-64c²=(6à)²-(8c)²=(6a-8c)(6a+8c)

1-a⁴c²=(1)²-(a²c)²=(1-a²c)(1+a²c)

-25c²+9a²=9a²-25c²=(3a)²-(5c)²=(3a-5c)(3a+5c)