A motorboat goes 30 km upstream and returns. The speed of the stream is 5 km/h and the total time is 4 hours 30 minutes (4.5 h). Let boat speed in still water be x km/h. Then 30/x-5 + 30/x+5 = 4.5 simplifies to which quadratic?

Question

Accepted Answer

3x^2 - 40x - 75 = 0. 30(x+5) + 30(x-5) = 4.5(x^2 - 25). So 60x = 4.5x^2 - 112.5. Multiply by 2: 120x = 9x^2 - 225, i.e. 9x^2 - 120x - 225 = 0, divide by 3: 3x^2 - 40x - 75 = 0.

A motorboat goes 30 km upstream and returns. The speed of the stream is 5 km/h and the total time is 4 hours 30 minutes (4.5 h).
Let boat speed in still water be $x$ km/h. Then $\frac{30}{x - 5} + \frac{30}{x + 5} = 4.5$ simplifies to which quadratic?

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More Class 10 Roots by Factorisation practice

A motorboat goes 30 km upstream and returns. The speed of the stream is 5 km/h and the total time is 4 hours 30 minutes (4.5 h).Let boat speed in still water be x km/h. Then x−530​+x+530​=4.5 simplifies to which quadratic?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 Roots by Factorisation practice

A motorboat goes 30 km upstream and returns. The speed of the stream is 5 km/h and the total time is 4 hours 30 minutes (4.5 h).
Let boat speed in still water be $x$ km/h. Then $\frac{30}{x - 5} + \frac{30}{x + 5} = 4.5$ simplifies to which quadratic?