展开 (2pix+4pi)(x+5)

解答

展开

(2 π x + 4 π) (x + 5)

2 π x^{2} + 14 π x + 20 π

求解步骤

(2 π x + 4 π) (x + 5)

使用 FOIL 方法:

(a + b) (c + d) = a c + a d + b c + b d

a = 2 π x, b = 4 π, c = x, d = 5

= 2 π xx + 2 π x \cdot 5 + 4 π x + 4 π 5

= 2 π xx + 2 \cdot 5 π x + 4 π x + 4 \cdot 5 π

化简

2 π xx + 2 \cdot 5 π x + 4 π x + 4 \cdot 5 π : 2 π x^{2} + 14 π x + 20 π

= 2 π x^{2} + 14 π x + 20 π

e x p an d \frac{2 ( x + 3 )}{5 ( 2 x - 1 )}

e x p an d (- 3 \cdot e + 3 \cdot z)^{2}

e x p an d r \cdot e^{j (θ + π)}

e x p an d x^{2} - 2^{2}

e x p an d e (2 x + 3 y - 2 z + 5)