1. (8x-.3.) ²=64x²-48x.+9
2. 3x+5y-7,5x-8,12y= -4,5x -3,12y
3
a) -2x(3xy-5y)=-6x²y+10xy
b) (5x+3)²=25x²+30x+9
c) (4a-7)(4a+7)=16a²-49
d) (2x²)³×14x ²=8x^6·14x²=112x^8
4.a)25x²-16y²=(5x-4y)(5x+4y)
b) 7x la puterea 4+56x=7x(x³+8)=7x(x³+2³)=7x[(x+2)³-6x(x+2)]=7x[(x+2)(x+2-6x)]=7x(x+2)(2-4x)