1. 4sin210°-3√2*cos(-135°)=4sin(180°+30°)-3√2cos(180°-45°)=
=4*(-sin30°)-3√2*(-cos 45°)=4*(-1/2)+3√2*(√2/2)=-2+3=1
2. 2ctg(5π/4)+√3tg(-5π/6)=2ctg(π+π/4)-√3tg(5π/6)=2ctgπ/4-√3tg(π-π/6)=2*1-√3*tg(π/6)=2-√3*(√3/3)=2-1=1
3. cos²(-5π/2+α)+cos²(8π-α)+2ctg(-3π/2+α)*ctg(5π-α)=
=cos²(5π/2-α)+cos²(8π-α)-2ctg(3π/2-α)*ctg(5π-α)=
=cos²(π/2-α)+cos²α-2tgα*(-ctgα)=sin²α+cos²α+21+2=3
1-х,2-х+1,3-х+2,4-х+3
(х+2)(х+3)-х(х+1)=42
х²+3х+2х+6-х²-х=42
4х=36
х=9-1 число
Ответ 9,10,11,12
<span>а) 1/2*√(12)-2√(27)+√(75) = 1\2*2</span>√3-2*3√3+5√3 = √3-2√3+5√3 = 4√3<span>
б) 3*√(2)*(5*√(2)-√(32)) = 3</span>√2*(5√2-4√2) = 3√2*√2 = 3*2 = 6<span>
в) (4-5*√(2)) = 16 - 2*4*5</span>√2+25(√2)² = 16 - 40√2 + 50 = 66-40√2<span>
</span>
<span>1/2 (4/5x+5/6)+(3/4x+5) при х=2
4/10x+5/12+3/4x+5
8/10+6/4+5/12+5=
(96+180+50)/120+5=
326/120+5=240/120+158/120+5=
2+5+1 19/60=8 19/60
</span>
(sin b)^2-2sin5b*cos5b+(cos5b)^2-1=1-sin10b-1=-sin10b