Выражения (3a+5)(3a-6)+30 8x-(3x+1)(5x+1) (x-3)(x++x) (y+2)(y+3)-y(y-1) 3b^2+(8-3b)(b+5) 8p-(3p+8)(2p-5) a(a-3)+(a+1)(a+4) (c+2)c-(c+3)(c-3) надо

(3a+5)(3a-6) +30 = 9a²-18a+15a-30+30= 9a²-3a =
можно вынести общий множитель:
= 3a(3a-1)

8х -(3х+1)(5х+1) = 8х -(15х²+3х+5х+1)=
= 8х - 15х²-8х-1 = -15х²-1

(х-3)(х+5)- (х²+х) = х²+5х -3х-15-х²-х=
= х-15

(у+2)(у+3)-у(у-1) = у²+3у +2у +6 - у²+у =
= 6у+6 = 6(у+1)

3b²+(8-3b)(b+5) = 3b² +8b +40 -3b²-15b=
= -7b+40 

8p -(3p+8)(2p-5)= 8p - (6p²-15p +16p-40)=
= 8p -( 6p² +p-40) = 8p -6p²-p+40=
= -6p² +7p+40

a(a-3) + (a+1)(a+4) = a²-3a + a²+4a +a+4 =
= 2a²+2a+4 = 2(a²+a+2)

(c+2)c -(c+3)(c-3)= c²+2c -(c²-3²) =
=c²+2c-c²+9 =2c+9