solvefor r,A=pir^2

解答

求解

r, A = p i r^{2}

无解

求解步骤

A = p i r^{2}

替代

r = x + y i

A = p i (x + y i)^{2}

展开

p i (x + y i)^{2} : - 2 p x y + i p (x^{2} - y^{2})

A = - 2 p x y + i p (x^{2} - y^{2})

将

A

改写成标准复数形式:

A + 0 i

A + 0 i = - 2 p x y + i p (x^{2} - y^{2})

复数仅在实部和虚部均相等时才相等改写为方程组:

[A = - 2 p x y 0 = p x^{2} - p y^{2}]

[A = - 2 p x y 0 = p x^{2} - p y^{2}] : 无解

r = x + y i

代回

无解

f a c t or x^{3} - 9

so l v e f or A, b 2 A = \frac{1}{2} h (b_{1} + b_{2})

so l v e f or x, e^{l n (x^{2})} - 16 = 0

so l v e f or r, V = \frac{1}{3 p i r ^{2} h}

so l v e f or t, - lo g_{10} (12) = - (\frac{( lo g _{10} ( 2 ) )}{5.1}) t