Quadratic Equations - Problem solving

Hi,

I have to use quadratic equations to solve the two attached questions but I do not know how to for any of them.
The answer for 8 is 12 eggs and the answer for 9 is 13 eggs.

I would really appreciate any help!
Thanks :smile:

Original post by musicangel

Hi,

I have to use quadratic equations to solve the two attached questions but I do not know how to for any of them.
The answer for 8 is 12 eggs and the answer for 9 is 13 eggs.

I would really appreciate any help!
Thanks :smile:

eggs must be very cheap in the US

Reply 2

TeeEm

19

Original post by musicangel

Hi,

I have to use quadratic equations to solve the two attached questions but I do not know how to for any of them.
The answer for 8 is 12 eggs and the answer for 9 is 13 eggs.

I would really appreciate any help!
Thanks :smile:

shameful ...

so many people around and we are all too lazy to help.

Here it comes the first one

x(x+5) = 84

can you see why?
do you know how to solve it?

Reply 3

musicangel

OP

13

Original post by TeeEm

shameful ...

so many people around and we are all too lazy to help.

Here it comes the first one

x(x+5) = 84

can you see why?
do you know how to solve it?

Thank you so much for this!
I managed to solve it but I do not know why you multiply x and (x+5).

Reply 4

danconway

14

Original post by musicangel

Thank you so much for this!
I managed to solve it but I do not know why you multiply x and (x+5).

x is the profit and (x+5) is the number of eggs.

So you have x profit (per egg) times the number of eggs, which is (x+5).

Like (in a different scenario) if you make a profit £2 per chocolate and you sell 5 chocolates, you'd do 5 x £2 and you'd make £10 in total.

(edited 9 years ago)

Reply 5

TeeEm

19

Original post by musicangel

Thank you so much for this!
I managed to solve it but I do not know why you multiply x and (x+5).

danconway answered the question ...

Reply 6

musicangel

OP

13

Original post by danconway

x is the profit and (x+5) is the number of eggs.

So you have x profit (per egg) times the number of eggs, which is (x+5).

Like (in a different scenario) if you make a profit £2 per chocolate and you sell 5 chocolates, you'd do 5 x £2 and you'd make £10 in total.

Thank you so much! This makes sense now! :smile:

Reply 7

musicangel

OP

13

Does anyone know the method for question 9?

Reply 8

danconway

14

Original post by musicangel

Does anyone know the method for question 9?

Do you fancy coming up with an equation for the situation? Remember the total price of something is the number of things times the price per thing. In this scenario, there are two products to consider.

Reply 9

TenOfThem

18

Original post by musicangel

Does anyone know the method for question 9?

Yes

It is the same as the method for q8

Did you actually understand the method for q8

Reply 10

musicangel

OP

13

Original post by danconway

Do you fancy coming up with an equation for the situation? Remember the total price of something is the number of things times the price per thing. In this scenario, there are two products to consider.

Would it be

x(x-8)+(x-2)(x-3)-175=0
x^2-8x + x^2-5x+6-175=0
2x^2 - 13x - 169 = 0

and then solving it?

Reply 11

danconway

14

Original post by musicangel

Would it be

x(x-8)+(x-2)(x-3)-175=0
x^2-8x + x^2-5x+6-175=0
2x^2 - 13x - 169 = 0

and then solving it?

Exactly!

Reply 12

musicangel

OP

13

Original post by danconway

Exactly!

Thank you all so much!
This has really helped me! :biggrin:

Reply 13

Dylann

21

Original post by TeeEm

eggs must be very cheap in the US

Fun fact: US eggs aren't allowed in European supermarkets and European eggs aren't allowed in US supermarkets. The reasons why contradict each other :rolleyes:

Posted from TSR Mobile

Reply 14

TeeEm

19

Original post by Dylann

Fun fact: US eggs aren't allowed in European supermarkets and European eggs aren't allowed in US supermarkets. The reasons why contradict each other :rolleyes:

Posted from TSR Mobile

Reply 15

musicangel

OP

13

I don't understand what the two questions attached mean.
Once again, I would really appreciate any help.
Thanks! :smile:

Original post by musicangel

I don't understand what the two questions attached mean.
Once again, I would really appreciate any help.
Thanks! :smile:

Do you know what the reciprocal of a number is?

Do you know how to translate the English phrase "x exceeds y by 3" into a mathematical statement relating x and y?

Reply 17

musicangel

OP

13

Original post by davros

Do you know what the reciprocal of a number is?

Do you know how to translate the English phrase "x exceeds y by 3" into a mathematical statement relating x and y?

I don't know what the reciprocal of a number is.
Would it be y + 3 = x or y = x - 3 depending what the subject is?

Original post by danconway

Exactly!

Eggsactly surely?

Reply 19

davros

16

Original post by musicangel

I don't know what the reciprocal of a number is.
Would it be y + 3 = x or y = x - 3 depending what the subject is?

The reciprocal of a number is 1 divided by that number, so the reciprocal of 3 is 1/3 and the reciprocal of x is 1/x.

Correct - if x exceeds y by 3 then x = y + 3.

Now you can set up the equation for your first new problem :smile:

Quadratic Equations - Problem solving

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