展开 ((85+r)(95-r))/((10-2r)^2)

解答

展开

\frac{( 85 + r ) ( 95 - r )}{( 10 - 2 r ) ^{2}}

\frac{8075 + 10 r - r ^{2}}{100 - 40 r + 4 r ^{2}}

求解步骤

\frac{( 85 + r ) ( 95 - r )}{( 10 - 2 r ) ^{2}}

(10 - 2 r)^{2} = 100 - 40 r + 4 r^{2}

= \frac{( r + 85 ) ( - r + 95 )}{100 - 40 r + 4 r ^{2}}

乘开

(85 + r) (95 - r) : 8075 + 10 r - r^{2}

= \frac{8075 + 10 r - r ^{2}}{100 - 40 r + 4 r ^{2}}

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