



 
Hi Simon. I assume the boats started next to each other before the hour of travel. Let x = the speed of the faster boat. Then x2 is the speed of the slower boat. They traveled for the same length of time (1 hour). Since speed times time equals distance, that means the fast boat went x(1) = x km and the slow boat went (x2)(1) = x2 km. The two directions are perpendicular, which means that you can draw a right triangle with the right angle representing the starting point and the hypotenuse representing the distance between the boats after one hour. Thus you have a right triangle whose legs are x and x2 km and whose hypotenuse is 10 km. What does Pythagoras tell you about the relationship of these quantities? Can you use that to create a quadratic equation? Does it factor? Hope this helps,  


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