展开 pi(-14r+64)*r^2

解答

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π \cdot (- 14 \cdot r + 64) \cdot r^{2}

- 14 π r^{3} + 64 π r^{2}

求解步骤

π (- 14 r + 64) r^{2}

= π r^{2} (- 14 r + 64)

使用分配律:

a (b + c) = ab + a c

a = π r^{2}, b = - 14 r, c = 64

= π r^{2} (- 14 r) + π r^{2} \cdot 64

使用加减运算法则

+ (- a) = - a

= - 14 π r^{2} r + 64 π r^{2}

14 π r^{2} r = 14 π r^{3}

= - 14 π r^{3} + 64 π r^{2}

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