2^-2 would become 1/2^2 which becomes 1/4.
Cuando has simplificado la ecuación lo mas posible y las expresiones de los dos lados quedan iguales, hay soluciones infinitas. Pero, dado que lo has simplificado y son diferentes, no hay solución.
1.) 7x = 12 + 7x - 12
=> 7x = 7x => infinita solución
2.) x - 11 = 11 + x
=> x = 22 + x => no solución
3.) 2(4x - 6) = 8(x + 2)
=> 8x - 12 = 8x + 16 => 8x = 8x + 28 => no solución
4.) 2x - 9 = 2x - 9
=> infinita solución
5.) 8 + 4x = 4x + 10
=> 4x = 4x - 2 => no solución
Answer:
r = 
Step-by-step explanation:
So we need to complete the square for both parts of the equation
First though we can add the 6 to the other side so we have x² + 2x + y² + 4y = 6
So first we can complete the square for x² + 2x
To do so we need to use
to figure out the number we need to add to both sides
In this case our b is 2, so substituting this in we get 
Here we add 1 to both sides and now we have x² + 2x + 1 + y² + 4y = 6 + 1
Now we can follow the same steps to complete the square for y² + 4y
Here our b is 4, so substituting this in we get 
Now we add 4 to both sides and now we have x² + 2x + 1 + y² + 4y + 4 = 6 + 1 + 4
Now condensing everything we have (x + 1)² + (y + 2)² = 11
The formula for a circle is (x - h)² + (y - k)² = r²
In our equation we have r² = 11
To find the radius we need to take the square root of both sides
to get r = 
I'm assuming it's 57. Because 1/2 can equal .5 and 56.5+.5=57