(a^6 * a^-3) / a^2 =
= ( a^(6 - 3)) / a^2 =
= a^3 / a^2 =
= a^2*a / a^2 =
= a
2,6х - 18,4 - 13 + 4,4х = 19,6
7х = 19,6 + 18,4 + 13
7х = 51
х = 51/7
х= 7 2/7
3x-y=7
3y+2x=1
--------------------
y=3x-7
3(3x-7)+2x=1
------------------
y=3x-7
9x-21+2x=1
---------------------
y=3x-7
11x=22
----------------------
y=3x-7
x=2
---------------------
y=3.2-7
x=2
----------------
y=-1
x=2
--------------------
P(2,-1)
==========
[cos105⁰(cos277⁰sin172⁰-cos7⁰sin82⁰]/(2√2)⁻²=
=(2√2)²·cos105⁰·[1/2(sin(172⁰-277⁰)+sin(172⁰+277⁰))-1/2(sin(82⁰-7⁰)+sin(82⁰+7⁰))]=
=4·2·1/2·cos105⁰·(sin(-105⁰)+sin449⁰-sin75⁰-sin89⁰)=
=4·cos105⁰·(-sin105⁰+sin(2π+89⁰)-sin75⁰-sin89⁰)=
=-4·cos105⁰·sin105⁰-4·cos105⁰·sin75⁰=
=-2·sin210⁰-4·1/2·(sin(75⁰-105⁰)+sin(75⁰+105⁰)=
=-2sin(π+30⁰)-2[(sin(-30⁰)+sin180⁰)]=
=-2(-sin30⁰)-2[(-sin30⁰)+0]=2sin30⁰+2sin30⁰=4sin30⁰=4·(1/2)=2