1.а)(5-b)(5+b)-2b(b-3)=25-b2-2b2+6b=6b+25
б)-5y(y+3)+(y-4)^2=-5y2-15y+y2-8y+16=16-4y2-23y
в)3(x-2)^2-3x2=3x2-12x+12-3x2=12-12x
2.а)9x2-x6=x2(3-x)(3+x)
б)x4-6x2+9=(x2-3)^2
3. (y-3)(y2+3y+9)-y(y-4)(y+4)=y3-27-y3+16y=16y-27
Если y=1,5, то 16y-27=16*1,5-27=24-27=-3
4.а)(x-8)^2-25y2=x2-16y+64-25y2=(x-5y)(x+5y)-16(4-y)=-16(4-y)(x-5y)(x+5y)
б)a2-b2-a+b=(a-b)(a+b)-(a-b)=(a+b)(a-b)^2
в)x6+8= ?
5.(a+b)^2+(a-b)^2=2(a2+b2)
a2+2ab+b2+a2-2ab+b2=2(a2+ba)
2a2+2b2=2(a2+b2)
2(a2+b2)=2(a2+b2)
6.b2+25+10b=0
b(b+10)=-25
b=-25 или b+10=-25
b=-25-10
b=-35