Побудуйте график ривняння з двома зминами.
1) 5x-2y=4
2) 3x+5y=1
3) 4x+5y=25
4) 2x-4y=32

Решение
1)  sina = 3/5
cosa = (+ -) √(1 - sin²a) = (+ -)√(1 - (3/5)²)) = (+ -)√(16/25) = (+ -) (4/5)
tga = sina/cosa
tga = 3/5 : 4/5 = 3/4
tga = 3/5 : (-4/5) = - 3/4
tga * cos²a = (3/4) * (4/5)² = (3*16)/(16/25) =  12/25
tga * cos²a = ( - 3/4) * (4/5)² = (- 3*16)/(16/25) =  - 12/25
tga * cos²a = tg0 * cos²0 = 0 * 1 = 0
2)  cosa = 5/13
sinx = (+ -)√(1 - cos²a) = (+ -)√(1 - (5/13)²) = (+ -) √(144/169) = (+  -) (12/13)
ctga = cosa/sina
ctga = 5/13 : (12/13) = 5/12
ctga =  5/13 : (- 12/13) = -  5/12
ctga * sin²a = 5/12 * 144/169 = 60/169
ctga * sin²a = - 5/12 * 144/169 = - 60/169

1) х² -2х = х+2-х²
х² - 2х - х +х² - 2 = 0
2х² - 3х - 2 =0
D=(-3)² - 4*2*(-2) = 9+16 = 25 = 5²
x1= (3 - 5)/(2*2) = -2/4 =-0.5
x2 =(3+5)/4 = 8/4 = 2

2) 3х² -8х + 13 = (х-5)²
3х² - 8х + 13 = х² - 10х + 25
3х² - 8х + 13 - х² + 10х - 25 =0
2х² +2х -12 = 0                             |÷2
x²+x - 6 =0
D=1² - 4*1*(-6) = 1 +24 = 25 = 5²
x1= (-1-5)/ (2*1) = -6/2 =-3
x2= (-1+5)/2 = 4/2=2

3) (x+1)²=(x-2)²
x²+2x+1 = x² -4x +4
x² +2x + 1 - x² +4x - 4 =0
6x  - 3 =0
6x= 3
x=3/6 = 1/2
x=0.5

4)(x-10)² = (1-x)²
x²-20x +100 = 1 -2x+x²
x² -20x +100 -1 +2x -x²=0
18x + 99 =0
x=99/18 = 11/2
x=5.5

5) условие можно прочитать по-разному:
(x+x)/3 = 8
2x/3 =8
2x= 3*8
2x= 24
x=24/2
x=12
или 
x    +   (x/3) = 8            |*3
3x +x = 8*3
4x=24
x=24/4
x= 6

6) x+1-5(x-5)(5-x)+5 = ???   условие не корректно.

7)  
х/2   +  х/4 = -3/2             | *4
2x +x = - 3/2   *  4
3x= - 6
x=-6/3
x=-2

8)(x/2) +(x/4) +x= -49/4       |*4
2x +x +4x = -49
7x=-49
x= -49/7
x=-7

9) 6 - (x/3) = х/7                  | * (7*3)
126 -  7x = 3x
-7x-3x=-126
-10x=-126
x= (-126) / (-10)
x= 12.6

10) (13+x)/3    - 3 =4x             |*3
13+x  - 9 = 12x
4+x= 12x
12x-x=4
11x=4
x=4/11

11) x-(x/3) = 1/2         |*6
6x - 2x = 3
4x=3
x=3/4