Toán Lớp 8: b) xy{3.[2(1 – 2x) – 5(x – 1)] + 2[2(4 – y) – 5(y- 2)]} – 4xy(x-y)
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Toán Lớp 8: b) xy{3.[2(1 – 2x) – 5(x – 1)] + 2[2(4 – y) – 5(y- 2)]} – 4xy(x-y)
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xy\left\{ {3\left[ {2\left( {1 – 2x} \right) – 5\left( {x – 1} \right)} \right] + 2\left[ {2\left( {4 – y} \right) – 5\left( {y – 2} \right)} \right]} \right\}\\
– 4xy\left( {x – y} \right)\\
= x.y.\left\{ {3\left( {2 – 4x – 5x + 5} \right) + 2\left( {8 – 2y – 5y + 10} \right)} \right\}\\
– 4{x^2}y + 4x{y^2}\\
= x.y\left[ {3.\left( {7 – 9x} \right) + 2.\left( {18 – 7y} \right)} \right] – 4{x^2}y + 4x{y^2}\\
= xy\left( {21 – 27x + 18 – 14y} \right) – 4{x^2}y + 4x{y^2}\\
= xy\left( {39 – 41y} \right) – 4{x^2}y + 4x{y^2}\\
= 39xy – 41x{y^2} – 4{x^2}y + 4x{y^2}\\
= 39xy – 4{x^2}y – 37x{y^2}
\end{array}$