展开-1/(14pi)(-cos(70pit)+1)

解答

展开

- \frac{1}{14 π} (- cos (70 π t) + 1)

\frac{cos ( 70 π t )}{14 π} - \frac{1}{14 π}

求解步骤

- \frac{1}{14 π} (- cos (70 π t) + 1)

使用分配律:

a (b + c) = ab + a c

a = - \frac{1}{14 π}, b = - cos (70 π t), c = 1

= - \frac{1}{14 π} (- cos (70 π t)) + (- \frac{1}{14 π}) \cdot 1

使用加减运算法则

- (- a) = a, + (- a) = - a

= \frac{1}{14 π} cos (70 π t) - 1 \cdot \frac{1}{14 π}

化简

\frac{1}{14 π} cos (70 π t) - 1 \cdot \frac{1}{14 π} : \frac{cos ( 70 π t )}{14 π} - \frac{1}{14 π}

= \frac{cos ( 70 π t )}{14 π} - \frac{1}{14 π}

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