1) a) (4x+y)²=(4x)²+2*4x*y+y²=16x²+8xy+y²
b) (7m-3n)²=(7m)²-2*7m*3n+(3n)²=49m²-42mn+9n²
c) (6y-1)²=(6y)²-2*1*6y+1²=36y²-12y+1
d) (b+c³)² = b² +2b*c³+(c³)²=b²+2bc³+c^6
2) a) x²+(5x-3)²= x²+(5x)²-2*3*5x+9²=x²+25x²-30x+9=26x²-30x+9
b) (p-2c)²+3p²=p²-2*2c+(2c)²+3p²=4p²-4c+4c²=4(p²-c+c²)
3) a)(5x-y)(5x+y)=(5x)²-y²=25x²-y²
b) (5b+1)(1-5b)=1²-(5b)²=1-25b²
4) a) 9p²-4= (3p)²-2²=(3p-2)(3p+2)
b) 1-25x²=1²-(5x)²=(1-5x)(1+5x)