been stuck on this question for a while now, the answer is 3/4, can someone please tell me what to do?
x Turn on thread page Beta
Find the term independent of x in the expansion of (x^2 - 1/2x)^3 watch
- Thread Starter
- 15-05-2016 22:26
- Official Rep
- 17-05-2016 23:40
Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.
You can also find the Exam Thread list for A-levels here and GCSE here.
Just quoting in Puddles the Monkey so she can move the thread if needed
Spoiler:Show(Original post by Puddles the Monkey)
- 18-05-2016 09:04
You want the component of the expansion with a negative exponent to cancel out with the positive exponent. X^2 has a positive exponent. Now multiplying X^2 with (-0.5x^-1)^2 will give a term independent of x (X^2 times X^-2 is 1). Now you need to consider the binomial coefficient in the expansion. B(3,1)=B(3,2)=3. 3*(-0.5)^2=3/4.
- 18-05-2016 09:05
Check binomial theorem if you are still unsure.