展开 tcos(wt)u(t^2-1)

解答

展开

t \cdot cos (wt) \cdot u (t^{2} - 1)

t^{3} u cos (wt) - t u cos (wt)

求解步骤

t cos (wt) u (t^{2} - 1)

= t u cos (wt) (t^{2} - 1)

使用分配律:

a (b - c) = ab - a c

t u cos (wt) (t^{2} - 1) = t u cos (wt) t^{2} - t u cos (wt) \cdot 1

= t u cos (wt) t^{2} - t u cos (wt) \cdot 1

化简

t u cos (wt) t^{2} - t u cos (wt) \cdot 1 : t^{3} u cos (wt) - t u cos (wt)

= t^{3} u cos (wt) - t u cos (wt)

e x p an d \frac{1}{6 x} (x^{2} + 2)^{3}

e x p an d p (3, - 5) y q (- 6, 6)

e x p an d - \frac{2}{( x - 1 ) ( x + h - 1 )}

e x p an d lo g_{7} (x^{2} + 5) - lo g_{10} (7) (x^{2} + 3)

e x p an d (x^{\frac{1}{4}} + y^{\frac{1}{4}})^{4}