展开 cos(2t)[h(t-pi/2)]

解答

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cos (2 t) [h (t - \frac{π}{2})]

t h cos (2 t) - \frac{πh cos ( 2 t )}{2}

求解步骤

cos (2 t) (h (t - \frac{π}{2}))

去除括号:

(a) = a

= cos (2 t) h (t - \frac{π}{2})

= h cos (2 t) (t - \frac{π}{2})

使用分配律:

a (b - c) = ab - a c

a = cos (2 t) h, b = t, c = \frac{π}{2}

= cos (2 t) h t - cos (2 t) h \frac{π}{2}

= t h cos (2 t) - \frac{π}{2} h cos (2 t)

\frac{π}{2} h cos (2 t) = \frac{πh cos ( 2 t )}{2}

= t h cos (2 t) - \frac{πh cos ( 2 t )}{2}

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e x p an d \frac{9}{( x + 1 ) ^{2}}

e x p an d \frac{c x + k}{( x - p ) ^{2}}