Year 12s: what will be the first way you research your future options? >>

C4 Binomial Expansion Questions

Please could you help me with these questions

(3+x)^-2

(5-x)^-2

(4+3x)^-2

Thanks

do you know the expansion formula ?
first you need to factor something out of the bracket so that the constant is 1, so for the first one you would factor 3 out, so you'd have
3^-2 (1+x/3)^-2, then you can use the formula

(edited 8 years ago)

Reply 2

Chloe_Louise1

Yeah I know the formula, I'd just like to check my answers

Reply 3

Alex621

Original post by Chloe_Louise1

Yeah I know the formula, I'd just like to check my answers

how many terms are you asked to find

up to x cubed

i got 1/9 - x/9 + (x^2)/27 - (4x^3)/242 + ... for the first one

Reply 6

Chloe_Louise1

I got 1/9 - 1/9x + 2/27x^2 - 10/243x^3

Reply 7

Alex621

Not sure if you care anymore lol but I just tried them again and this is what I got...

Is there anywhere you can check the answers?? I feel like i've done it wrong

IMG_1764.jpg458.4KB

Reply 8

razzor

Original post by AlexParmenter

Not sure if you care anymore lol but I just tried them again and this is what I got...

Is there anywhere you can check the answers?? I feel like i've done it wrong