Christian Lawson-Perfect

Christian Lawson-Perfect commented on Extract common factors of polynomials 8 years, 6 months ago

When b is a list, random(something except [b]) will exclude the list containing the list b, not each element of b. So the square brackets are wrong - you want random(something except b).

Christian Lawson-Perfect on Laws of Indices 8 years, 6 months ago

Gave some feedback: Has some problems

Christian Lawson-Perfect commented on Laws of Indices 8 years, 6 months ago

This mainly looks good.

Try to avoid long runs of maths in-line with text - they're quite hard to read. Put long bits of maths in display mode, and don't be afraid to use lots of paragraph breaks.

Christian Lawson-Perfect on Surds simplification 8 years, 6 months ago

Gave some feedback: Has some problems

Christian Lawson-Perfect commented on Surds simplification 8 years, 6 months ago

The prompt for part b is hopelessly generic! "Match each product with the equivalent surd" might do, but that's not quite right either. Also think about how the numbers are laid out - would it be better to put the products down the side and collected surds on top? As it is, I can rule out a few combinations without thinking, like $\sqrt{44}$ is obviously not equal to $\sqrt{30}$.

Part c: I would repeat $\sqrt{n} = $ before the gap-fill. As stated, how is "$\sqrt{300} = \sqrt{100} \times \sqrt{3}$, so $\sqrt{300} = ?? \times \sqrt{3}$" different to $\sqrt{100} = ??$". Maybe just $\sqrt{300} = \text{[gapfill]} \times \sqrt{3}$ would do.

Part d: for "simplify" to make sense here, I think you need to give the hint that they can be simplified to whole numbers.

Part e: instead of [1] and [2], write $a$ and $b$. I got $\frac{\sqrt{6}}{\sqrt{3}}$, which it expected me to write as $\frac{\sqrt{18}}{3}$. I'd write that as just $\sqrt{2}$. Can you set it up so there's only one way of writing it? Making sure the top and bottom of the original fraction are coprime might do it.

Part f: I had to reduce the fraction - you should say that in the prompt. "Rationalise the denominator of this expression and reduce to lowest terms".

In parts g, h and i, the big expression is REALLY big - have you formatted it as a header? I don't think you need the "= ?" bit, or "and select the correct answer from the list of options". 

None of the parts of this question really lead on from each other - you could split this into several smaller questions.

Advice

Some numbers not in LaTeX in part a. "Roots are necessary but not sufficient conditions for surds" isn't completely clear - I'd say "all surds are roots, but not all roots are surds".

Part e: this might be incredibly pedantic, but does "the denominator is $\sqrt{6}$" sound better than "\sqrt{6} is the denominator" to you?

A few sentence of a similar form to "This gives the final answer as:"; I would say "So the final answer is:". 

Some wordy explanation of what's happening at each step, or a description of the plan of attack, in part f wouldn't go amiss.

Part g: It's not true that you can't multiply by those things, it just doesn't help. Get someone else to read that paragraph and have a go at rewriting it: it's a bit long and easy to get lost in. There's an unhelpful "simply" in there, too.

I have a few problems with this sentence: "To be able to do a question like $\frac{2}{\sqrt2+\sqrt8}+\frac{1}{3}$ which requires you to add fractions, you need to have the same denominator." 

• $\frac{2}{\sqrt2+\sqrt8}+\frac{1}{3}$ isn't a question, it's an expression.
• "you need to have the same denominator" isn't a complete phrase - the same as what? 

Try:

To add $\frac{2}{\sqrt2+\sqrt8}$ to $\frac{1}{3}$, you must put write both terms with the same denominator."

Likewise, "the question is now $\frac{2}{3\sqrt2}+\frac{1}{3}$" isn't right. You could say "the expression is now ...".