展开 ((b-2a)^2)/2

解答

展开

\frac{( b - 2 a ) ^{2}}{2}

\frac{b ^{2}}{2} - 2 ba + 2 a^{2}

求解步骤

\frac{( b - 2 a ) ^{2}}{2}

(b - 2 a)^{2} = b^{2} - 4 ba + 4 a^{2}

= \frac{b ^{2} - 4 ba + 4 a ^{2}}{2}

使用分式法则:

\frac{a \pm b}{c} = \frac{a}{c} \pm \frac{b}{c}

\frac{b ^{2} - 4 ba + 4 a ^{2}}{2} = \frac{b ^{2}}{2} - \frac{4 ba}{2} + \frac{4 a ^{2}}{2}

= \frac{b ^{2}}{2} - \frac{4 ba}{2} + \frac{4 a ^{2}}{2}

数字相除:

\frac{4}{2} = 2

= \frac{b ^{2}}{2} - 2 ba + 2 a^{2}

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