3) 121m²-88mn+16n²=(11m-4n)²
4) 24ab+36a²+4b²=(6a+2b)²
5) a⁶-4a³b+4b²=(a³-2b)²
6) 25p¹⁰+q⁸+10p⁵q⁴=(5p⁵+q⁴)²
3) (a+3)³-27=(a+3)³-3³=(a+3-3)((a+3)²-3(a+3)+3²)=a(a²+6a+9-3a-9+9)=
=a(a²+3a+9)
4) (a-7)³+8=(a-7)³+2³=(a-7+2)((a-7)²-2(a-7)+2²)=(a-5)(a²-14a+49-2a+14+4)=
=(a-5)(a²-16a+67)
5) (a+4)³-27=(a+4)³-3³=(a+4-3)((a+4)²+3(a+4)+3²)=
=(a+1)(a²+8a+16+3a+12+9)=(a+1)(a²+11a+37)
6) (a-9)³+64=(a-9)³+4³=(a-9+4)((a-9)²-4(a-9)+4²)=
=(a-5)(a²-18a+81-4a+36+16)=(a-5)(a²-22a+133)
Tg t/(tg t + Ctg t) = ?
a)tg t = Sin t/Cos t
б) tg t + Ctg t = Sin t/Cos t + Cos t /Sin t = (Sin² t + Cos ²t)/Cos t Sin t= 1/Cos tSin t
в) Sin t/Cos t : 1/Cos tSin t = Sin t /Cos t ·Cos t Sin t /1= Sin²t
В приложении дается ответ.
1)3x-2y=7 /.3
2x+3y=1 /.2
-------------
9x-6y=21
4x+6y=2 /+
-------------------
13x=23, x= 23/13
3x-2y=7 /.2
2x+3y=1 /.(-3)
-----------------------
6x-4y=14
-6x-9y=-3 /+
---------------------
-13y=11, y=-11/13
/x,y/=/23/13,-11/13/
=================
2)2(3x-y)-5=2x-3y
5-(x-2y)=4y+16
-----------------------------
4x-y=5
-x-2y=11
-------------
y=4x-5
-x-2(4x-5)=11,-9x+10=11,-9x=1, x=-1/9
y=4(-1/9)-5=-4/9-5,y=-49/9
/x,y/=/-1/9,-49/9/