Question 509175
26.Solve.
15t^2 + 7t = 2
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15t^2 + 7t - 2 = 0
(3t + 2)*(5t - 1) = 0
t = -2/3, 1/5
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Solve:#14
Rowing. Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5 km/h. Find Abby’s speed in still water.
10/(b-5) + 10/(b+5) = 3
10(b+5) + 10(b-5) = 3*(b-5)*(b+5) = 3b^2 - 75
20b = 3b^2 - 75
3b^2 - 20b - 75 = 0
*[invoke solve_quadratic_equation 3,-20,-75]
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Ignore the negative solution
speed =~ 9.34 km/hr