3)4x²+12x=4x(x+3)
4)36a²-b²=(6a)²-b²=(6a+b)(6a-b)
5)c²+9-6c=c²-6c+3²=(c-3)²
6)5t(k-p)-(p-k)=5t(k-p)+(k-p)=(k-p)(5t+1)
7)4xy-8y-x²+2x=4y(x-2)-x(x-2)=(x-2)(4y-x)
x=102, y=-3/4 , (102-2)(-3-102)=100(-105)=-10500
8)a²-9b²+a+3b=(a²-9b²)+(a+3b)=(a+3b)(a-3b)+(a+3b)=(a+3b)(a-3b+1)
9)4ˇ24-4ˇ21=4ˇ21(4ˇ3-1)=4ˇ21(64-1)=63 × 4ˇ21=63 ×4 ×4ˇ20=126 × 2 × 4ˇ20
126 ×2 ×4ˇ20 /126 = 2 × 4ˇ20