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Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

If f(x)= sqrt4x+9+2, which inequality can be used to find the domain of f(x)?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)