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secondary 3 | A Maths
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need help with this qn,, pls explain too :)
Date Posted: 3 years ago
Views: 282
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done
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To get the terms in x^2, we need to multiply
- 1 by some term in x^2
- cx by some term in x^1
- 4x^2 by some constant term
To get the terms in x^3, we need to multiply
- 1 by some term in x^3
- cx by some term in x^2
- 4x^2 by some constant term
Once you anticipate these, you will need terms up to x^3 from the expansion of (1/4 - 2x)^6.
- 1 by some term in x^2
- cx by some term in x^1
- 4x^2 by some constant term
To get the terms in x^3, we need to multiply
- 1 by some term in x^3
- cx by some term in x^2
- 4x^2 by some constant term
Once you anticipate these, you will need terms up to x^3 from the expansion of (1/4 - 2x)^6.
Date Posted:
3 years ago
It’s a matter of knowing how you can get terms in x^2 from the full expansion.
i did that to try and get coefficient for x^2 first but i got a different ans from 1/1024
i also didnt know that i have to find the unknown c as i thought i can just ignore it and solve for the ans
i also didnt know that i have to find the unknown c as i thought i can just ignore it and solve for the ans
Let me check if I went careless. Sometimes I do make errors
Ok, checked the specific numbers already. No mistake.
In the full expansion of the two brackets, as we can see, there are three terms in x^2. These must all be added up to become a single term in x^2.
In reality, for (1 + x)^2, there is one constant term, two terms in x and one term in x^2. But we can simplify the two terms in x to become 2x.
That 1/1024 thing is actually the coefficient of x^2 which is given in the question. As for the 1/1024 in my expansion; it’s 4/4096 being simplified to become 1/1024.
In reality, for (1 + x)^2, there is one constant term, two terms in x and one term in x^2. But we can simplify the two terms in x to become 2x.
That 1/1024 thing is actually the coefficient of x^2 which is given in the question. As for the 1/1024 in my expansion; it’s 4/4096 being simplified to become 1/1024.
thx :) btw do u help with emaths?
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