Math Help

[Giantzebra]

Objects moving in two dimensions can be hard to track, unless you use calculus to handle the motion. If an object is moving so its X coordinate follows the equation X = 2t + 1 and its Y coordinate follows the equation Y = t2 + 2, where t is the time in seconds, what is the object’s two-dimensional speed at t = 2 seconds?
How do you solve this problem? 

Don't you just differentiate both the equations? So x = t and y = 2t. Plug in t = 2 and you get (2,4).

It's asking for speed so you do differentiate. Speed (not a vector) is just the positive value of velocity (vector). The first equation should provide distance. Differentiating it once will provide velocity and another time will output acceleration.

But the correct answer to the question was √20 feet per second