Question 1057766
Let s be the speed of the boat in still water. Then:
17/(s+4) + 17/(s-4)=10
17(s-4)+17(s+4)=10s²-160
10s²-34s-160=0
5s²-17s-80=0
Using the quadratic formula, i.e. {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}, we get two roots: 6.04626276242 and -2.64626276242. Throwing out the negative result, we get the speed of the boat in still water to be 6.04626 kph. &#9786;&#9786;&#9786;&#9786;