Maths Core 1

cn anyone plz help me on the following qs: a curve with the equation y=x^2+px+q, where p and q are integers, passes through the points (2,3) and (-3,-2). Find the values of p and q. thnx u :smile:

Reply 1

Dualcore

If you sub the values into the equation you will get two equations in terms of p and q which you can then solve simultaneously

Reply 2

shana_t

Original post by Dualcore

If you sub the values into the equation you will get two equations in terms of p and q which you can then solve simultaneously

I tried to do it but it didn't work, the answer is y=x^2+2x-5
So p=2
And q=-5
Cn u show me the step by step working out please if u cn

Posted from TSR Mobile

Reply 3

m4ths/maths247

Original post by shana_t

I tried to do it but it didn't work, the answer is y=x^2+2x-5
So p=2
And q=-5
Cn u show me the step by step working out please if u cn

Posted from TSR Mobile

Write down what you did.
It may help people spot the error. :smile:

Reply 4

shana_t

Original post by m4ths/maths247

Write down what you did.
It may help people spot the error. :smile:

(2,3) -->(2)^2 +2p+q=0

--> 4+2p+q=0
2p+q=-4
and (-3,-2) --> (-3)^2+-3p+q=0
--> 9-3p+q=0
-3p+q=-9

then...
2p+q=-4
+
-3p+q=-9
___________
5p=5
p=1
and p=-6
Its completely wrong!

(edited 10 years ago)

Reply 5

ghostwalker

Original post by shana_t

(2,3) -->(2)^2 +2p+q=0

--> 4+2p+q=0
2p+q=-4

You've substituted in the value of x, but not the value of y.

At the point (2,3) you would have (2)^2 +2p+q=3

A similar problem exists with your second equation.

Reply 6

shana_t

Original post by ghostwalker

You've substituted in the value of x, but not the value of y.

At the point (2,3) you would have (2)^2 +2p+q=3

A similar problem exists with your second equation.

omg, thank u soo much, i got it now :biggrin:

Reply 7

ghostwalker

Original post by shana_t

i got it now :biggrin:

Reply 8

EXTREMEninja

What the post above said. You should have: 4 + 2p + q = 3 for the first equation. Then work out the second equation by using the other coordinates, and solve the simultaneous equations.