Номер 1 2х+2 =4
4х=4х
4:4
х=1
A)Xb=-b/2a Xb=-8/8=-1 Yb=4*(-1)^2-8-1=4-9=-5
b)x=6/(-6)=-1 y=-3+6+2=5
в)-1/-2=1/2 y=-1/4+1/2-1=-3/4
г)-10x^4+5x^2=y t=x^2 -10t^2+5t=y tв=-5/-20=1/4 Xв=+-1/2 y1=-10*(-1/2)^4+5*1/4=-10/16+5/4=-5/8+5/4 -5/8+10/8=5/8 y2=5/8
cos(П/2 + x) = -sinx = 12/13
sinx = -12/13
cosx = корень из (1 - sin^2x) = корень из (1 - 144/169) = корень из 25/169 = 5/13
т.к. <span>x принадлежит промежутку ( </span><span> ; </span><span> ), то cosx = -5/13</span>
<span>tg2x = 2tgx/(1 - tg^2x) </span>
<span>tgx = sinx/cosx = (-12/13)/(-5/13) = 12/5</span>
<span>tg2x = 2*(12/5)/[1 - (12/5)^2] = (24/5)/(-119/25) = -120/119</span>