The answers would be a and then ctell me if you need an explaination
In doing this you can use the factoring method to do this faster. Start by dividing both sides by two to simplify the equation. X^2 now equals 100.
You can move 100 to the other side of the equation so that x^2-100=0. You can now factor and solve using the zero product property.
x^2-100=0
(x+10)(x-10) = 0
x equals 10 and -10.
The answer is 9.2, because when the number behind the number being rounded is 5 or above, you round up. if the number was 9.14, it would be rounded down to 9.1 :)
The answer of the question is D