以升冪序展開下列算式直至x^4項。
1a. (3x^2 - 2 )^4
1b. (2x+1/x)^3
1c. Expand (3x^2 - 2)^4 (2x+1/x)^3 in ascending powers of x as far as the term in x^2.
以升冪序展開 (3x^2 - 2)^4 (2x+1/x)^3 直至x^2項。
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2a. Expand (1-ax)^5(x+2)^8 in ascending powers of x as far as the term in x^2.
以升冪序展開(1-ax)^5(x+2)^8 直至x^2項。
2b. If the coefficient of x is -1536, find the possible value of a.
若x的系數為-1536，求a的可取值。
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3. (px^2+1/x)^k is expanded in descending powers of x, where k is a positive integer and p>10. If the 5th term of the expansion is independent of x and is equal to 135, find the values of p and k.
設k為正整數，且p>0。在 (px^2+1/x)^k 以解冪序的展式中，若其第五項不含x且等於135，求p及k的值。
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最好用英文答，但中文都冇所謂
唔該晒你地:'(
要有埋 Step，十萬感激，40點。
更新1:
點都要幫我解決第2a同埋3 /_\ 唔該晒
