<span>(Cosx+sinx)^2=cos2x</span>
<span>cos^2x +2sinxcosx+sin^2x=cos2x</span>
<span>sin2x+1-cos2x=0</span>
<span>2sinxcosx+sin^2x+cos^2x-cos^2x+sin^2x=0</span>
<span>2sinx(sinx+cosx)=0</span>
<span>sinx=0</span>
<span>x=ПN</span>
<span>sinx=-cosx/ /cosx</span>
<span>tgx=-1</span>
<span>x=-п/4+пN</span>
Ответ:
Объяснение:
-x²-12x+21=0
x²+12x-21=0
D=144+84=228
x₁=(-12-2√57)/2=-6-√57
x₂=(-12+2√57)/2=√57 -6
Ответ: (-6-√57); (√57 +6)
...................Решение на фото...................
3x + 4y = 7
5x - 4y = 9
------------------- +
8x = 16
x = 2
y = (7 - 3x)/4 = (7 - 6)/4 = 1/4
ОТВЕТ
( 2; 1/4)
0,25=1\4
4\17=16\68
1\4=17\68
17\68>16\68
0,25>4\17