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# C1 question watch

1. this is from the latest ocr paper:

given that: (x-p)(2x^2 +9x+10) = (x^2 - 4)(2x +q)

for all values of x, find the constants of p and q.

this is sooo hard for one of the first questions.
can someone tell me how to work this out please
2. (Original post by cooldudeman)
this is from the latest ocr paper:

given that: (x-p)(2x^2 +9x+10) = (x^2 - 4)(2x +q)

for all values of x, find the constants of p and q.

this is sooo hard for one of the first questions.
can someone tell me how to work this out please
Hard???
Just expand out and equate co-efficients.....
3. (Original post by H.C. Chinaski)
Hard???
Just expand out and equate co-efficients.....
sorry im still a newbie at C1. could you explain
4. (Original post by cooldudeman)
sorry im still a newbie at C1. could you explain
Expand the brackets for each side and then equate the terms which are the same, ie. all the x^2 terms, as they have to equal the same amount so for example for the x^2 terms, you get '9x^2-2px^2=qx^2', and when you have enough of these either there will be one with values that you can plug in or you solve using simultaneous equations.
5. thanks
6. I remember this question, stared at it straight at the end with no clue on how to do it . I got it right though, I think one was 2 and the other was 5. I did what was mentioned above.
7. If you're having trouble with questions of a similar nature then I will suggest that you ask yourself if mathematics is really the subject for you...
8. (Original post by cooldudeman)
this is from the latest ocr paper:

given that: (x-p)(2x^2 +9x+10) = (x^2 - 4)(2x +q)

for all values of x, find the constants of p and q.

this is sooo hard for one of the first questions.
can someone tell me how to work this out please
I'd expand to get 2x^3 +9x^2 +10x -2px^2 -9px -10p = 2x^3 + qx^2 - 8x -4q

Cancel 2x^3 to get 9x^2 +10x -2px^2 -9px -10p = qx^2 - 8x -4q
then:

10x - 9px = -8x so rearrange and stuff to get 9p = 18 (p=2)

And 9x^2 - 2px^2 must equal qx^2

So you get 9 - 2p = q and therefore 9-2(2) = q so q=5

Then you can substitute these values in, rearrange the large equation and then solve the quadratic with a suitable method.

Then
9. (Original post by hassi94)
I'd expand to get 2x^3 +9x^2 +10x -2px^2 -9px -10p = 2x^3 + qx^2 - 8x -4q

Cancel 2x^3 to get 9x^2 +10x -2px^2 -9px -10p = qx^2 - 8x -4q
then:

10x - 9px = -8x so rearrange and stuff to get 9p = 18 (p=2)

And 9x^2 - 2px^2 must equal qx^2

So you get 9 - 2p = q and therefore 9-2(2) = q so q=5

Then you can substitute these values in, rearrange the large equation and then solve the quadratic with a suitable method.

Then
yeah i understand, thanks for the help
10. give the chapter another read, think.

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