展开 (20(-1+k/n)^3+20(-1+k/n)^2)*1/n

解答

展开

(20 (- 1 + \frac{k}{n})^{3} + 20 (- 1 + \frac{k}{n})^{2}) \cdot \frac{1}{n}

\frac{20 ( - n + k ) ^{3}}{n ^{4}} + \frac{20 ( - n + k ) ^{2}}{n ^{3}}

求解步骤

(20 (- 1 + \frac{k}{n})^{3} + 20 (- 1 + \frac{k}{n})^{2}) \frac{1}{n}

= \frac{1}{n} (20 (- 1 + \frac{k}{n})^{3} + 20 (- 1 + \frac{k}{n})^{2})

使用分配律:

a (b + c) = ab + a c

\frac{1}{n} (20 (- 1 + \frac{k}{n})^{3} + 20 (- 1 + \frac{k}{n})^{2}) = \frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{3} + \frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{2}

= \frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{3} + \frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{2}

化简

\frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{3} + \frac{1}{n} \cdot 20 (- 1 + \frac{k}{n})^{2} : \frac{20 ( - n + k ) ^{3}}{n ^{4}} + \frac{20 ( - n + k ) ^{2}}{n ^{3}}

= \frac{20 ( - n + k ) ^{3}}{n ^{4}} + \frac{20 ( - n + k ) ^{2}}{n ^{3}}

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