binomial expansion

[atomic lintel]

Have I done the first question right?

And how do I do the second question because I’m pretty sure I got it wrong

[safe isle]

,rotate

[safe isle]

is it not

$$4^5(1-\frac{3}{4}x^-1)^5$$

[frail river]

Aurora 🪻

[safe isle]

and then u find the first using binomial expansion rule

so $$b_n = nx + \frac{n(n-1)}{1*2}x...$$

[frail river]

Aurora 🪻

[safe isle]

omg texit is so fun

[atomic lintel]

@safe isle how

Where do you get the 1- from?

[safe isle]

i forgot the 1+ lol

$$(1+x)^n = 1+ nx + \frac{n(n-1)}{12}x^2 + \frac{n(n-1)(n-2)}{12*3}x^3...$$

[frail river]

Aurora 🪻

[atomic lintel]

I see

My teacher didn’t teach us this rule

I assume it’s in the formula booklet tho

[safe isle]

yeah for edexcel

@atomic lintel

[atomic lintel]

I do ocr mei

I’m sorry to be a pain but could you do a full on solution so I can compare it to what I’ve done

[safe isle]

its alr and sure

@atomic lintel give me 5 minutes just wanna try put this all into latex haha i got the paper solution too if u just really need it rn

$$\textbf{Expanding } (4-\frac{3}{x})^5$$

$$\text{Step 1. Make it look nice}$$
$$(4-3x^{-1})^5 $$
$$\text{Step 2. Take the 4 out, so we can get it in the format which our formula uses:} $$
$$ (1+ax)^n $$
$$ 4^5(1-\frac{3}{4}x^{-1})^5$$
$$\text{Again, step 1. Make it look nice}$$ \

[frail river]

Aurora 🪻

[clever lark]

Latex wizard