5.
2x-y=4 2x-y=4 2(3-2y)-y=4 6-4y-y=4 -5y=-2 y=2/5
x+2y=3 x=3-2y x=3-2y x=3-2y x=3-2y x=3-2*(2/5)=11/5
3.
a)8m+m²-n²-8n=8m-8n+m²-n²=8(m-n)+(m-n)(m+n)=(m-n)(8+m-n)
б)36x²-81y⁴=(6x-9y²)(6x+9y²)
в)x²+10xy+25y²=(x+5y)²=(x+5y)(x+5y)
1.
(2-m)²-(m+2)(m-1)=4-4m+m²-m²+m-2m+2=6-5m