1 11m ^ 5 - 5m ^ 2 * n ^ 3 + n ^ 4 2 - a ^ 8 + 2b ^ 5 + 4a * b ^ 8 - 1 ; 3 11x * y ^ 4 + 6x ^ 4 * y ^ 4 + 5x ^ 4 + y ^ 4 4 -2x+3y-xyz; 5 a * b ^ 5 * c + 2ab * c ^ 4 - 15abc ;

Решение
1)  (x+3)(x-4)=-12
x² - x - 12 = - 12
x(x - 1) = 0
x₁ = 0
x₂ = 1
ответ: х₁ = 0 : х₂ = 1

2)  (3x-1)^2=1
3x - 1 = - 1
3x = 0
 x₁ = 0

3x - 1 = 1
 3x = 2
x₂ =  2/3 
ответ: х₁ = 0; х₂ = 2/3

3)  (2x+3)(3x+1)=11x+30
6x² + 11x + 3 = 11x + 30
6x² = 27
x² = 9/2
x₁ = - 3√2/2
x₂ = 3√2/2
ответ: x₁ = - 3√2/2; x₂ = 3√2/2

4)  18-(x-5)(x-4)=-2
x² - 9x + 20 = 20
x(x - 9) = 0
x₁ = 0
x₂ = 9
ответ: x₁ = 0 ; x₂ = 9

5)  5x+(2x+1)(x-3)=0
5x + 2x² - 5x - 3 = 0
2x² - 3 = 0
2x² = 3
x² = 3/2
x₁ = - √6/3
x₂ = √6/3

6)  x^2-5=(x-5)(2x-1)
x² - 5 = 2x² - 11x + 5
x² - 11x + 10 = 0
x₁ = 1
x₂ = 10
ответ: x₁ = 1 ; x₂ = 10

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