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Would much appreciate any help. I have an exam in 2 days.
x^3 can be made when X^2 * X or when X^3 times any number
so binomially expand the first part to give (1-X + 0.25X^2)
expand the second part to to the X^3 term. this gives (1+ 14X + 84X^2 +280X^3 ...)
multiply the relevant terms together. so 1*280X^3 + X * 84X^2 + 0.25X^2 * 14X
this gives 367.5X^3
so the coefficient is 367.5
Any questions just ask :)
is there something missing in the question?.. in-between the squared and the (1+2x)^7 ?
Thank you so much Pui Pui, your method helped so much, and you made it really simple.
The answer you got was incorrect, probably a small mistake but I used your method to get the correct answer: 199.5
Really good explanation.
Thank you again for your help, I really appreciate it :D x
your very welcome
found my mistake!! it should have been -X* 84X^2
I ALWAYS make sign mistakes. what a nightmare!
glad that i could help. Good luck in the exam:)