Sin=корень(1-9/25)=корень(16:25)=4:5=0.8
tg=sin/cos=-4/5*5/3=-4/3
ctg=1/tg=-3/4
39.
1)
д=16-4×4×1=0
х=-4/2=-2
2)
д=144-4×4×9=0
х=12/2×4=3/2=1 1/2=1.5
38.
2)=-(1/9а^2-1/3аб+1/4б^2)=
=-(1/3а-1/2б)^2
5x(z-y)+6m(z-y)=(5x+6m)(z-y)
3,21 : 0.3 + 2.42 =10.7 + 2.42 = 13.12
5 : 0.2 - 13 = 25 - 13 = 12
1/4 + 3.17 = 0.25 + 3.17 = 3.42
5/7 + 1/3 + 1/21 = 15/21 + 7/21 - 1/21 = 21/21 = 1
3/5 - 3/8 = 24/40 - 15/40 = 9/40 = 0.225
9/7 : 3/28 = (9 * 28) : (7*3) = 252/21 = 12
2/5 - 0.52 * 5/26 = 0.4 - 2.6/26 = 0.4 -0.1 = 0.3
Незннаю не проходили извини