у=1/2+1/2x-2y
3-2x+2-8x=1/5
5-8x=1/5
24/5=8x
x=3/5
8x - 3(2x - 1) ≤ - 2
8x - 6x + 3 ≤ - 2
2x ≤ - 2 - 3
2x ≤ - 5
x ≤ - 2,5
x ∈ ( - ∞ ; - 2,5]
<span>1). 5(3-5a)^2-5(3a-7)(3a+7)=5(9-30a+25a²)×2-5(9a²-49)=2(45-150a+125a²)-45a²+245=90-300a+250a²-45a²+245=250a²+335-300a=250a²-300a+335
2). <span>(m-1)^2-4(m+1)^2-6(m+1)(m-1)=m²-2m+1-4(m²+2m+1)-6(m²+1)=m²-2m+1-4m²-8m-4-6m²-6=-9m²-10m-9=9m²+10m+9</span></span>