№4
1. (x+b)^2=x^2+2xb+b^2
2. (c-2)^2=c^2-4c+4
3. a^2-49=(a-7)(a+7)
4. y^3+125=(y+5)(y^2-5y+25)
5. d^3-27=(d-3)(d^2+3d+9)
6. (x+2)^2=x^2+4x+4
7. (y-4)^2=y^2-8y+16
№2
1. (a+b)^2=a^2+2ab+b^2
2. (c-4)^2=c^2-8c+16
3. 9-a^2=(3-a)(3+a)
4. x^3+8=(x+2)(x^2-2x+4)
5. 125-8x^3=-8x^3+125=-(2x-5)(4x^2+10x=25)
6. (3-b)^3=-(b-3)^3=-b^3+9b^2-27b+27
7. (1+a)^3=(a+1)^3=a^3=2a^2+3a+1