1.
a) (3x-y)²=9x²-6xy+y²
b) (-6n-2)²=36n²+24n+4
c)) (-7c+8x³)²=49c²+112cx³+64x^6
d) (b-13a)(13a+b)=(b-13a)(b+13a)=b²-169a²
e) (-5m^4+3)(3+5m^4)=-(3-5m^4)(3+5m^4)=-(9-25m^8)=25m^8-9
2.
a)-36c-3(5-6c)²=-36c-3(25-60c+36c²)=-36c -75+180c-108c²=
=-108c²+144c-75
b)(b-1)(1+7b)-b(4-3b)=(7b-1)(7b+1)-b(4-3b)=49b²-1-4b+12b=
=49b²+8b-1
c)(2k-3)(3+2k)-(3k-5)²-30k=(2k-3)(2k+3)-(9k²-30k+25)-30k=
=4k²-9-9k²+30k-25-30k=-5k²-34
3.
a)x²-(x-4)(x+4)=2x
x²-(x²-16)=2x
x²-x²+16=2x
2x=16 // : 2
X=8
b)
(3y+1)²-9(y+1)(y-1)=8y-1
9y²+6y+1-9(y²-1)=8y-1
9y²+6y+1-9y²+9=8y-1
6y+10=8y-1
2y=11
Y=11/2=5,5