1)(а-18)(а+18)=а^2-324 2)(11-х)(11+х)=121-x^2 3)(6+х)(х-6)=(х+6)(х-6)=x^2-36
4)144-у^4=(12+у^2)(12-y^2) 5)x^2-1=(x+1)(x-1) 6)49x^2-64y^2=(7x+8y)(7x-7y)
7)(2x-3)^2= 4x^2-10x^2+9 8)(5y+1)^2=25y^2+10y+1 9)x^2-24x+144=(x-12)^2
10)x^2+x+1\9=(x+1\3)^2 11)16x^2+8x+1=(4x+1)^2 12)(7-x)(7+x)=49-x^2
13)(9-x)(x+9)=(9-x)(9+x)=81-x^2 14)(x+3)(x-3)=x^2-9 15)(y+8)(8-y)=(8+y)(8-y)=64-y^2
16)(x-9)^2=x^2-18x+81 17)(x+6)^2=x^2+6x+36 18)(4-x)^=16-8x+x^2
19)(x^2+1)^2=x^4+x^2+1