FP2 Edexcel Inequalities Tricky Question

https://8fd9eafbb84fdb32c73d8e44d980d7008581d86e.googledrive.com/host/0B1ZiqBksUHNYTnpyeF8xQlZweHc/CH1.pdf

Exercsie A Question 8

Please help

https://8fd9eafbb84fdb32c73d8e44d980d7008581d86e.googledrive.com/host/0B1ZiqBksUHNYTnpyeF8xQlZweHc/CH1.pdf

Exercsie A Question 8

Please help

https://8fd9eafbb84fdb32c73d8e44d980d7008581d86e.googledrive.com/host/0B1ZiqBksUHNYTnpyeF8xQlZweHc/CH1.pdf

Exercsie A Question 8

Please help

https://8fd9eafbb84fdb32c73d8e44d980d7008581d86e.googledrive.com/host/0B1ZiqBksUHNYTnpyeF8xQlZweHc/CH1.pdf

Exercsie A Question 8

Please help

There are a lot of things going on in that question

Which bit are you stuck on?

Is it the first step?

which part are you experiencing difficulty in understanding?

Thanks for your replies.

I get to the part where the inequality is greater and equal to zero, and then the stage after that they say that:

0 is greater than and equal to the inequality, I don't understand why this is done.

Thanks for your replies.

I get to the part where the inequality is greater and equal to zero, and then the stage after that they say that:

0 is greater than and equal to the inequality, I don't understand why this is done.

That's because if you have:

$x>-y$ then by multiplying by -1 you'll get $-x<y$

That's what they have done with the quadratic if you look carefully I can expand more if you want me to

They've taken out a minus from the quadratic in the line before. When you multiply both sides by -1 of an inequality, what happens?

Thanks guys this clarifies things a bit better. The only problem I still have is that who does the (x+1)(x-2) not change.

Regards.

Thanks guys this clarifies things a bit better. The only problem I still have is that who does the (x+1)(x-2) not change.

Regards.

Because if the only way for it to change is if you take out another minus sign which you wouldn't need to do

(x+1)(x-2) [ (-4-2x-x^2) ] = (x+1)(x-2) [ -1* (4 + 2x + x^2) ]

= -1*(x+1)(x-2)(4+2x+x^2). (Then multiply by -1 and the inequality flips)

You take -1 out from the quadratic, you don't need to worry about the x+1 and x-2.

omg thank you so much I forgot that if you factored out the -1 of that bracket it could go to the front.

Really appreciate your help, I see it now.

Are you guys giving FP2 in June

omg thank you so much I forgot that if you factored out the -1 of that bracket it could go to the front.

Really appreciate your help, I see it now.

Are you guys giving FP2 in June

I am sitting FP2 this June too Good luck to you. Feel free to message me if you have any particular questions, or post on the forums.

Nice good luck to you too

Thanks.

Just one last question about this thread, do you think a question like that is more difficult than the standard fp2 inequalities questions given in exams?

Nice good luck to you too

Thanks.

Just one last question about this thread, do you think a question like that is more difficult than the standard fp2 inequalities questions given in exams?

No not really, that's a typical question.

Cool thanks

This question is probably the most difficult question I've seen for inequalities in FP2, mainly because of that quadratic that doesn't have any real roots - it's not immediately obvious that it doesn't matter when it comes to finding roots. The hidden -1 is also sneaky. Anyway you know what to do now so I wouldn't worry too much