1. 1) (5-b)(5+b)-2b(b-3)=25-b^2-2b^2+6b=-3b^2+6b+25
2) -5y(y+3)+(y-4)^2=-5y^2-15y+y^2-8y+16=-4y^2-23y+16
3) 3(x-2)^2-3x^2=3x^2-12x+12-3x^2=12-12x
2. 1) 9x^2-x^6=(3x-x^3)(3x+x^3)
2) x^4-6x^2+9=(x^2-3)^2
3. (2y-1)(4y^2+2y+1)-y(y-1)(y+1)=8y^3+4y^2+2y-4y^2-2y-1-y^3+y=7y^3+y-1
y=1.5=>
7(3/2)^3+3/2-1=189/8+1/2=193/8=24 1/8
4. 1) (x-8)^2-25y^2=(x-8-5y)(x-8+5y)
2) a^2-b^2-a+b=(a-b)(a+b)-(a+b)=(a-b)(a+b-1)
3) x^6-8=(x^2-2)(x^4+2x^2+4)