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magisfadooo

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17. Write a quadratic equation to find two consecutive odd natural n

I keep getting these wrong please help

17.   Write a quadratic equation to find two consecutive odd natural numbers whose product is 63.  Then find the numbers.

18.   A tennis ball is launched with an initial velocity of 24.5 m/s from the edge of a cliff that is 117.6 meters above the ground. Which quadratic equation could be used to correctly determine when the ball will hit the ground:

4.9t2 + 24.5t + 117.6 = 0

-4.9t2 - 24.5t + 117.6 = 0

-4.9t2 + 24.5t - 117.6 = 0

4.9t2 + 24.5t - 117.6 = 0

-4.9t2 + 24.5t + 117.6 = 0

19. Solve the equation you chose in question 18 to determine when the ball will hit the ground. (HINT: If you don't get one of the answers listed for this question, then maybe you chose the wrong equation in #18. Use this opportunity to double check your work!)

t = 8 seconds

t = 4 seconds

t = 3 seconds

t = -3 seconds

The ball will never reach the ground.

20. Using the same equation, determine when the ball is at a height of 49 meters.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

hi magisfadooo

Welcome to the forum. 

Q17.  Let n be one number.  The next odd number will be n+2.  Now multiply these and put equal to 63.  That's your equation.

Q18.  You know the initial velocity, the acceleration and the distance, and want the time.  The equation to use for that is

The wording doesn't make it clear if the initial velocity is upward or downward.  If up, then the ball will go up, and then come down with the same velocity, so it would seem sensible to use

u = 24.5;   a = +9.8; s = 117.6

So which quadratic did you use ?

If this won't work try u = -24.5  ie. have u going up rather than down.

Bob

ps.  It occurs to me that u could also be horizontal. 

Q20.  The equations given are for 117.6 so none of them will work for 49m.  I expect the questioner meant

u = 24.5;  a = 9.8;  s = 117.6 - 49;  which will lead to a different equation. 

These questions aren't from CompuHigh by any chance ?

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

http://www.mathisfunforum.com/search.ph … =742548021

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

Good morning bobbym,

How are you?

I'm not getting a result from that link.  Is this an earlier post on the same?

EDIT:  I searched and found it myself.  Hmmmm.  It is CompuHigh.  I wonder how I knew. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

Hi Bob;

I have been better and I have been worse. How goeth things there?

Looks like a phantom link.

http://www.mathisfunforum.com/viewtopic … 61#p326861

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

I found this:

http://www.mathisfunforum.com/viewtopic.php?id=16122

It's good to know that CompuHigh isn't bothering to change any questions.  After all, there may be many students who have come to rely on the public nature of the answers to make sure they get 20/20.  What was that you asked about cheating ?

How goeth things there?

Very good, thanks.  We had a three week holiday: flew to Vancouver; then Alaskan cruise to Glacier Bay; back to Vancouver; Rocky Mountaineer to Jasper (train); then finally to Bamff.  Great scenery; great hotels; really friendly people.   We saw 4 black bears, two coyotes, two elk and numerous hump back whales.  We also saw a squirrel chasing a stoat!  Yes, I thought it should be the other way round too.  The grizzlys were hiding. 

Now we've got lots of gardening to catch up. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

Hi Bob;

Do you mean Banff?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

I do indeed.  Too many places; too many hotel rooms.  Well spotted.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

If this is an image, it looks like heaven!

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

That looks like the place.  We stayed just out of shot on the left side of the river.  Our shots are still in the camera.  I'll try to get some posted soon.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

Would you have liked to stay there?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 17. Write a quadratic equation to find two consecutive odd natural n

No.  There's no place like home. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: 17. Write a quadratic equation to find two consecutive odd natural n

I have heard that before.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.