1) x=3-y
9-3y-2y=6
-5y=-3
y=3/5=0,6
x=3-0,6=2,4
2) x+3y+2y-x=5+3
5y=8
y=8/5=1,6
<span>x=3,2-3=0,2
</span>
Радиусы окружностей, описанные около правильных многоугольников равны:
R₃ =
R₄ =
R₆ = a
Тогда R₃ =
см
R₄ =
см
R₆ = 6 см.
В соответствии с этим:
А - 3
Б - 4
В - 2
1)
/////////////////////////////////////////////
--------(1)-------------------(2,5)--------------
\\\\\\\\\\\\\\\\\\\\\\\\\\
x∈(2,5;∞)
2){x≥1,5
{x≤3
//////////////////////////////////////////////////////
---------[1,5]----------------------[3]---------------
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
x∈[1,5;3]
3
/////////////////////////////////////////////////////
------------(-2)---------------------(-1,5)----------------
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
x∈(-2;-1,5)
4
{5x<5⇒x<1
{x<12
\\\\\\\\\\\\\\
---------(1)---------------------(12)-----------
///////////////////////////////////////////
x∈(-∞;1)
5
{x≤15
{x≥6
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
--------[6]------------------[15]-----------
/////////////////////////////////////////
x∈[6;15]
6
{x>0
{x≥-7
/////////////////////////////////////////////
----------[-7]--------------------(0)----------------
\\\\\\\\\\\\\\\\\\
x∈(0;∞)