The easiest way to find the square root of 55 is to use a calculator.
√55 ≈ 7.4161984871
Rounded to the nearest tenth, this is ...
√55 ≈ 7.4
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You can make a first approximation of the root by linearly interpolating between the roots of the perfect squares* on either side of 55.
√49 = 7
√64 = 8
√55 ≈ 7 +(55 -49)/(64 -49) = 7 6/15 = 7 2/5
√55 ≈ 7.4
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* For numbers greater than 3.3, this sort of approximation will give the value of the root accurate to the nearest tenth. The approximation is better for larger numbers.
It's A. All you have to remember here are your rules of translations. If there is side to side movement within a parabola it will be indicated within a set of parenthesis with the x coordinate. If there is no set of parenthesis with the x there is no side to side movement. The quantity tells us that the vertex has moved left 3 units.