Plug in for the variable x in the equation?

Question

Solve:

1.

-2x^2+x-1

X=2x

2.

x/x^2-4

x=2x

Answer 1

1. We know that X=2x, so X^2=2^2*x^2. Now substitute x=2x for x in the first equation, except use x^2=4x^2 in the first term. Then you get -8x^2+2x-1. But x=2X, so we divide by 2X and get -4x+1-1/2x, and we can substitute -2x=-4X and 2x=-x/2 to get -2x+1+2x, and the -2x cancels with the +2x, leaving 1.

2. This time we have x=2x, so x/x^2-4 is 2x/x^2-4. But given x=2x, we can multiply both sides by 2 to find 2x=4x, and substitute into the original expression to get 4x/x^2-4. Then we can divide the numerator and denominator of the first term through by x, and get 4/^2-4. This can't be reduced any further, so your answer is 4/^2-4.

Answer 2

impossible why are you asking these types of questions  

Answer 3

The equations cannot be solved. x = 2x is a contradiction.

Answer 4

Tricky question Macintosh.

But it looks like they are just doubling x to see what happens.

So here we go with the first one, wherever I see an "x" I will just replace it with 2x:

-2 * (2*x)^2 + 2*x -1

-2 * 4*x^2 + 2*x -1

-8*x^2 + 2*x - 1 and that is the simplest form

Now take a look at the second problem, let's plug in 2x everywhere and  use extra parentheses to make it clear what is going on:

(2*x)/((2*x)^2) -4

(2*x)/(4*x^2) - 4

1/(2*x) - 4 and that is the simplest form of the equation.

=) Deiesiera