1)0,8x-(0,7x+0,96)=7,10,8x-0,7x-0,96=7,1
0,1x=7,1+0,960,1х=8,06
х=8,06:0,1
х=80,6
2) x-0,5=2(0,3x-0,2),x-0,5=0,6x-0,4,
х-0,6х =0,5-0,4,
0,4х =0,1,
х=0,1:0,4
х=0,25
Ctg(π-α)=-ctgα
ctg(α+π)=ctgα
ctg(α+2π)=ctgα
-3ctgα-ctgα+ctgα=-3ctgα=-3·0,15=-0,45
(tg³x + tg²x) + ( -2tgx - 2) = 0
tg²x(tgx +1) - 2(tgx +1) =0
(tgx +1)(tg²x -2 ) = 0
tgx +1 = 0 или tg²x -2 = 0
tgx = -1 tg²x = 2
x = -π/4 + πk , k ∈Z tgx = +-√2
x = +-arctg(√2) + πn , n ∈Z