Запишите выражение в виде степени числа 3:
3+3+3+3^2+3^2+3^3+3^3+3^4+3^4+...+3^12+3^12

1) 3x - 4 = 8
3x = 12
x = 4

2)12 - 2x = - 10
- 2x = - 22
x = 11

3)2x + 3 = 10
2x = 7
x = 3,5

4) 14x - 7 = 28
14x = 35
x = 2,5

5) (x - 3)(15 - x) = 0
15x - x² - 45 + 3x = 0
- x² + 18x - 45 = 0
x² - 18x + 45 = 0
D = b² - 4ac = 324 - 4×45 = 324 - 180 = √144= 12
x₁ = 18 + 12/2 = 15
x₂ = 18 - 12/2 = 3

6) (2x - 20)(3 + 3x) = 0
6x + 6x² - 60 - 60x = 0
6x² - 54x - 60 = 0
D = 2916 - 4×6 × ( - 60) = 2916 + 1440 = 4356
x₁ = 54 + 66/ 12 = 10
x₂ = 54 - 66/12 = - 1

7)( 12 - 3x)(25 - 5x) =0
300 -  60x - 75x + 15x² = 0
15x² - 135x + 300 = 0
D = 18225 - 4 × 15 × 300 = 18225 - 18000 = √225 = 15
x₁ = 135 + 15/30 = 5
x₂ = 135 - 15/30 = 4

1//1
ctga=12/5
sin²a=1;(1+ctg²a)=1:(1+144/25)=1:169/25=25/169
sina=+-5/13
cosa=+-√(1-sin²a)=+-√(1-25/169)=+-√(144/169)=+-12/13
1/2
cosx=-3/5
sinx=√(1-cos²x)=√(1-9/25)=√(16/25)=4/5
2/1
cosa/(1+cos2a) -cosa=cosa/(2cos²a)- cosa=1/(2cosa) -cosa=
=(1-2cos²a)/(2cosa)=-cos2a/(2cosa)
2/2
Sin(п/2-х)+Cos(п+х)+Sin(п/2+х)=cosx-cosx+cosx=cosx
3/1
Cos(х-п/6)=Cos(x+п/6)+Sina
cos(x-π/6)-cos(x+π/6)=sinx
-2sin[(x-π/6-x-π/6)/2]*sin[(x-π/6+x+π/6)/2]=sinx
-2sin(-π/6)sinx=sinx
-2*(-1/2)*sinx=sinx
sinx=sinx
3/2
(1+tg²a)/(1+ctg²a)=tg²a
(1+tg²a):(1+1/tg²a)=tg²a
(1+tg²a):(tg²a+1)/tg²a=tg²a
(1+tg²a)*tg²a/(tg²a+1)=tg²a
tg²a=tg²a