展开 (-2cos(x)-4)^2

解答

展开

(- 2 cos (x) - 4)^{2}

4 cos^{2} (x) + 16 cos (x) + 16

求解步骤

(- 2 cos (x) - 4)^{2}

使用完全平方公式:

(a - b)^{2} = a^{2} - 2 ab + b^{2}

(- 2 cos (x) - 4)^{2} = (- 2 cos (x))^{2} - 2 (- 2 cos (x)) \cdot 4 + 4^{2}

= (- 2 cos (x))^{2} - 2 (- 2 cos (x)) \cdot 4 + 4^{2}

化简

(- 2 cos (x))^{2} - 2 (- 2 cos (x)) \cdot 4 + 4^{2} : 4 cos^{2} (x) + 16 cos (x) + 16

= 4 cos^{2} (x) + 16 cos (x) + 16

e x p an d e^{- 3 (t - 3)} - e^{- 3 (t - 5)}

e x p an d - 3 (ln (5 x) + 1)

e x p an d \frac{4000 ( s ^{2} + 4 s + 4 )}{s ( s + 10 ) ( s + 100 )}

e x p an d \frac{10 ( 12 - 15 )}{3}

e x p an d a cos (b (x - c)) + d