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#### Checkpoint description

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Published this.

#### Christian Lawson-Perfect3 years, 1 month ago

Gave some feedback: Ready to use

#### Christian Lawson-Perfect3 years, 1 month ago

Saved a checkpoint:

I've fixed a couple of typos, but otherwise this is OK!

#### Bradley Bush3 years, 1 month ago

Thank you for the feedback, I can see your logic, so I've changed it to your way of asking.

The inequality signs have been swapped to make sure the student is paying attention to their direction because of it's significance to the question.

Both graphs struggled to fit on the same figure so I have added another graph at the end with an brief bit of text to justify that both x ranges are the same.

#### Bradley Bush3 years, 1 month ago

Gave some feedback: Needs to be tested

#### Christian Lawson-Perfect3 years, 1 month ago

(I realise I contradicted Vicky's suggestion. Not sure if what you've done is exactly what she imagined, but it doesn't read clearly to me!)

#### Christian Lawson-Perfect3 years, 1 month ago

Gave some feedback: Has some problems

#### Christian Lawson-Perfect3 years, 1 month ago

The prompt doesn't actually say what should go in the first gap for each part. I know the statement says factorise first, but you should be absolutely clear what you want.

I'd have:

"Factorise $f(x)$:

$x^2+ax+b =$ [[gap]]

Hence, find the range of values for $x$ such that $x^2+ax+b \gt 0$."

You need a conjunction between the two inequalities at the end of parts a and b: "$x \gt ??$ OR $x \lt ??$" in part a, and $x \gt ??$ AND $x \lt ??$" for part b. If you want, you can make that a dropdown.

The inequality signs for part b are the other way round to part a. Why?

Part c doesn't make sense - you can't rearrange an inequality to get an equality. I'd ask them to rearrange to get something $\gt 0$ - this also makes sure they don't give the negation of what you're expecting - and then say "by factorising or otherwise, give the range of values for which $ax + b \gt x^2$. Keeping track of the inequality makes it easier to work out which way round the upper and lower bounds should go.

In the advice, I'd give examples of some values of $x$ that satisfy the inequality - in part a, a big negative value and a big positive value, and in part b a vlaue between the roots. For part c, I think it would be very helpful to show the graphs of $x^2$ and $ax+b$ on top of the graph of $x^2-ax-b$ to show that the inequality holds for the same values in both arrangements - i.e., $x^2 \gt ax+b$ exactly when $x^2-ax-b \gt 0$.

#### Bradley Bush3 years, 1 month ago

Gave some feedback: Needs to be tested

#### Bradley Bush3 years, 1 month ago

Gave some feedback: Has some problems

#### Bradley Bush3 years, 1 month ago

Gave some feedback: Needs to be tested

#### Bradley Bush3 years, 1 month ago

Thank you for the feedback, those typos were careless and hopefully they are all sorted now, I have also reworded the question for you.

I hate to disagree but I think that it would be useful for students who are struggling in particular to have the factorise step left in the question to give the student a mid way point. But if there is more logic behind removing the gap, I am happy to take it out.

#### Vicky Hall3 years, 1 month ago

Gave some feedback: Has some problems

#### Vicky Hall3 years, 1 month ago

Reword the questions here to say something like: find the range of values of $x$ for which ${function}>0$. You have told the student to factorise in the statement so you don't need to say it again. I would also remove the gap asking them to give the factorised form.

Have a check through the advice as I noticed a couple of typos and a rogue part d).

#### Bradley Bush3 years, 1 month ago

Gave some feedback: Needs to be tested

#### Bradley Bush3 years, 1 month ago

How do I allow either or answers for the gap in part a?

#### Bradley Bush3 years, 1 month ago

Created this as a copy of Solving linear inequalities.
Solving linear inequalities draft Adrian Jannetta 21/10/2018 10:22
Ida's copy of Solve quadratic inequalities draft Ida Landgärds 13/04/2018 09:16
Ida's copy of Solving linear inequalities draft Ida Landgärds 13/04/2018 09:16
Solving linear inequalities [L5 Randomised] Needs to be tested Matthew James Sykes 25/07/2018 10:51
cormac's copy of Solving linear inequalities draft cormac breen 24/10/2018 13:44
cormac's copy of Solve quadratic inequalities draft cormac breen 24/10/2018 13:46
Solving linear inequalities draft Xiaodan Leng 11/07/2019 01:43
Quiz: Solving linear inequalities draft Electronics Leeds 01/10/2019 21:06
ibrahim's copy of Solving linear inequalities draft ibrahim khatib 10/02/2020 15:39
Jan's copy of Solve quadratic inequalities draft Jan Hansen 03/05/2020 10:04
Ahmed's copy of Solving linear inequalities draft Ahmed Al-Razaz 19/05/2020 00:42
Solving linear inequalities Ready to use John Ian Keng 28/06/2020 09:42
Solving linear inequalities Ready to use John Ian Keng 28/06/2020 09:42
Solving linear inequalities Ready to use John Ian Keng 28/06/2020 09:43

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