展开 (e-2f)^2

解答

展开

(e - 2 f)^{2}

4 f^{2} - 4 e f + e^{2}

求解步骤

(e - 2 f)^{2}

使用完全平方公式:

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

a = e, b = 2 f

= e^{2} - 2 e 2 f + (2 f)^{2}

化简

e^{2} - 2 e 2 f + (2 f)^{2} : e^{2} - 4 e f + 4 f^{2}

= e^{2} - 4 e f + 4 f^{2}

改写为标准形式

= 4 f^{2} - 4 e f + e^{2}

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