# Math help (urgent)

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The curve y=p^x +2qx passes through the points (1,4) and (-1,-3/2)

Given that y<0 at x=-5 find the values of p and q

Any help would be greatly appreciated!

Thank you for reading

Given that y<0 at x=-5 find the values of p and q

Any help would be greatly appreciated!

Thank you for reading

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#2

(Original post by

The curve y=p^x +2qx passes through the points (1,4) and (-1,-3/2)

Given that y<0 at x=-5 find the values of p and q

Any help would be greatly appreciated!

Thank you for reading

**R146**)The curve y=p^x +2qx passes through the points (1,4) and (-1,-3/2)

Given that y<0 at x=-5 find the values of p and q

Any help would be greatly appreciated!

Thank you for reading

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(Original post by

Sub the points and solve the simultaneous equations.

**mqb2766**)Sub the points and solve the simultaneous equations.

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#4

(Original post by

Thank you!Sorry to disturb but by that do you mean (1,4) and (-1,-3/2)? or

**R146**)Thank you!Sorry to disturb but by that do you mean (1,4) and (-1,-3/2)? or

**y < 0 and x is -5**See what you get by subbing/solving the two points and think about why they've given you the extra constraint.

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(Original post by

The bold is not a point.

See what you get by subbing/solving the two points and think about why they've given you the extra constraint.

**mqb2766**)The bold is not a point.

See what you get by subbing/solving the two points and think about why they've given you the extra constraint.

I have gotten:

1=p^4+8q (1)

-3/2=p^-1-2q (2)

i Then did equation (2)x4 so it became:

-6=4p-8q

I have got -5=4p+p^4

I hope that is correct so far!

Thank you for your time again

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#6

(Original post by

Thank you once again i am beginning to understand this!

I have gotten:

1=p^4+8q (1)

-3/2=p^-1-2q (2)

i Then did equation (2)x4 so it became:

-6=4p-8q

I have got -5=4p+p^4

I hope that is correct so far!

Thank you for your time again

**R146**)Thank you once again i am beginning to understand this!

I have gotten:

1=p^4+8q (1)

-3/2=p^-1-2q (2)

i Then did equation (2)x4 so it became:

-6=4p-8q

I have got -5=4p+p^4

I hope that is correct so far!

Thank you for your time again

Last edited by mqb2766; 3 weeks ago

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(Original post by

You don't normally solve quartics at a level. Check the x-y values youve subbed. Also make sure you know what p^(-1) represents.

**mqb2766**)You don't normally solve quartics at a level. Check the x-y values youve subbed. Also make sure you know what p^(-1) represents.

This might be wrong but i redid the equation and i got

4=p+2q

-3/2=1/p-2q

5/2=1/p+p?

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#8

(Original post by

Sorry ive only recently started a levels so i may be a bit of a newbie,thank you for putting up with me

This might be wrong but i redid the equation and i got

4=p+2q

-3/2=1/p-2q

5/2=1/p+p?

**R146**)Sorry ive only recently started a levels so i may be a bit of a newbie,thank you for putting up with me

This might be wrong but i redid the equation and i got

4=p+2q

-3/2=1/p-2q

5/2=1/p+p?

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#9

**R146**)

The curve y=p^x +2qx passes through the points (1,4) and (-1,-3/2)

Given that y<0 at x=-5 find the values of p and q

Any help would be greatly appreciated!

Thank you for reading

y=px

2

+qx+r

at (0,0) we get,

0=p(0)

2

+q(0)+r

∴r=0

dx

dy

=2px+q →y=x,m=1

dx

dy

(0,0)

=2p(0)+q=1

⇒q=1

y=px

2

+q at (1,2)

2=p(1)

2

+1

⇒p=1

∴p=1,q=1,r=0

hope that i helped you

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#10

Last edited by mqb2766; 3 weeks ago

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(Original post by

Yes, so solve for p. If you multiply through by p it becomes a quadratic which is bread and butter ...

**mqb2766**)Yes, so solve for p. If you multiply through by p it becomes a quadratic which is bread and butter ...

(2p−1)(p−2)=0

Giving p=1/2 or 2

I assume you just sub that back in to find q as you usually do?

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#12

(Original post by

Thank you once again!I have gotten

(2p−1)(p−2)=0

Giving p=1/2 or 2

I assume you just sub that back in to find q as you usually do?

**R146**)Thank you once again!I have gotten

(2p−1)(p−2)=0

Giving p=1/2 or 2

I assume you just sub that back in to find q as you usually do?

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#13

(Original post by

Can you pls delete and read the sticky at the top of the forum about posting hints, not "solutions".

**mqb2766**)Can you pls delete and read the sticky at the top of the forum about posting hints, not "solutions".

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(Original post by

Sure. Then use the final constraint.

**mqb2766**)Sure. Then use the final constraint.

Im not sure where y<0 so x=-5 comes in though

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#15

(Original post by

I got q is 1.75 if p is 0.5 and q is 1 if p is 2

Im not sure where y<0 so x=-5 comes in though

**R146**)I got q is 1.75 if p is 0.5 and q is 1 if p is 2

Im not sure where y<0 so x=-5 comes in though

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#16

(Original post by

sorry i did not understand

**STARFIRE13245**)sorry i did not understand

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(Original post by

What happens to those solutions when x=-5?

**mqb2766**)What happens to those solutions when x=-5?

Thank you so much again and i wish you well in the future

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