√(27+10*√2)=√(25+2*5*√2+2)=√(5²+2*5*√2+(√2)²)=√(5+√2)²=5+√2.
1)–1/2у*(8у²+1/2у–4) =-1\2у*8у²-1\2у*1\2у-1\2у*(-4) =-4у³-1\4у²+2у=у*(-4у²-1\4у+2)
2)<span> 3–(1.5х–12.8)=45.8–4х
3-1,5х+12,8=45,8-4х
-1,5х+4х=45,8-12,8-3
3х=30
х=30\3
х=10</span>
(a-3)*2-a(5a-6)=2a-6-5a^2+6a=-5a^2+8a-6. при а=-0,5.