Quadratic word problem

[juliemariefort]

Will someone check this for me?

During the first part of a canoe trip, Jenny paddled 30 km at a certain speed. She then traveled 40 km at a speed of 5 km/hr slower. If the total time for the trip is 6 hours, what was the speed on each part of the trip?

t1 + t2 = 6

t1 = 30/r

t2 = 40/r-s

The quadratic equation is 0 = 6r^2 – 100r +150

Then I plug numbers into the quadratic formula.

I get t1 = 15 km/hr

T2 = 10 km/hr

Is this correct? I just want to make sure I understand it. It’s not as hard as I first thought.

Thanks.

 

[Mrspi]

Will someone check this for me?

During the first part of a canoe trip, Jenny paddled 30 km at a certain speed. She then traveled 40 km at a speed of 5 km/hr slower. If the total time for the trip is 6 hours, what was the speed on each part of the trip?

t1 + t2 = 6

t1 = 30/r

t2 = 40/r-s<------I think you mean 40 / (r - 5)

The quadratic equation is 0 = 6r^2 – 100r +150

Then I plug numbers into the quadratic formula.

I get t1 = 15 km/hr

T2 = 10 km/hr

Is this correct? I just want to make sure I understand it. It’s not as hard as I first thought.

Thanks.

You need to learn to check your own work.

If she travels 30 km at 15 km/h, how long does that take?
If she travels 40 km at 10 km/h, how long does it take?

What is the total of those two times? Is it the number of hours stated in the problem?

If so, you know your answer is correct.

(edited to fix a couple of typos)

 

[juliemariefort]

Yup, I realize that 2 + 4 = 6. I was just asking if I wrote it out correctly. Thanks for your input.