展开 pir^2(108-2pir)

解答

展开

π r^{2} (108 - 2 π r)

- 2 π^{2} r^{3} + 108 π r^{2}

求解步骤

π r^{2} (108 - 2 π r)

使用分配律:

a (b - c) = ab - a c

a = π r^{2}, b = 108, c = 2 π r

= π r^{2} \cdot 108 - π r^{2} \cdot 2 π r

= 108 π r^{2} - 2 ππ r^{2} r

化简

108 π r^{2} - 2 ππ r^{2} r : - 2 π^{2} r^{3} + 108 π r^{2}

= - 2 π^{2} r^{3} + 108 π r^{2}

e x p an d 2 (arctan (tan (t)) + \frac{π}{4})

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

s im pl i f y (1 + 3 \cdot i)^{4}

e x p an d \frac{9}{4 x ( 5 x + 3 )}

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