some math help?

Question

1. http://i209.photobucket.com/albums/bb248/pielover757/furlings13.jpg

2. http://i209.photobucket.com/albums/bb248/pielover757/furlings14.jpg

3. http://i209.photobucket.com/albums/bb248/pielover757/furlings15.jpg

4. http://i209.photobucket.com/albums/bb248/pielover757/furlings16.jpg

Answer 1

1) The answer is 6 so it is none of the above
2) D 6x^2+9x+4
3. A
4) E (should be 5 and -4)

Answer 2

The answers are as follow:
1. [E]
2. [D]
3. [A]
4. [E]

The detail solution to them are as follow:
1.

7*x = 12 + 5*x so 7*x - 5*x = 12 then 2*x = 12 hence x = 6!
So [E] is correct answer.

2.
You simply insert a number (like x = 1) to the given equation:
the result is :19
The only answer which gives 19 is answer [D] and to check, you multiply that to (x-2) and you get (6 * x^3 - 3*x^2 - 14*x -8)
So [D] is correct answer.

3.
24^(0.5) can be written as: (6*4)^0.5
4^(0.5) comes out of the square root as 2 and will be multiplied to 2 which will equals to 4*(6^0.5)
Then you multiply 3*(6^0.5) to the parentheses and you get:
12*6 + 9*(12^0.5)
12^0.5 equals to (4*3)^0.5
4 comes out of square root and becomes 2 and will be multiplied by 9 equals to 18
so the answer will finally be:
(72+18 * 3^0.5)
Hence [A] is correct answer!

4.
You may just substitute the given answer choices to the equation. None of them satisfy the equation.
The answer to this equation is "5 and -4".
Hence [E] is correct!

Answer 3

1. 7x = 12 + 5x
2x = 12
x = 6 [E]

2. 6x^2 + 9x + 4 [D]

3. 72 + 18sqrt(3) [A]

4. x^2 - x - 20 = 0
(x - 5)(x + 4) = 0
x = 5, -4 [E]