209/VB01. problem / Math - Solved Math Problems

MR-209 / 825c. problem

Find the cube of the given expressions:

$2 x - 3 y$

${(2 x - 3 y)}^{3}$

$= {(2 x)}^{3} + 3 \cdot {(2 x)}^{2} \cdot (- 3 y) + 3 \cdot 2 x \cdot {(- 3 y)}^{2} + {(- 3 y)}^{3}$

$= 8 \cdot x^{3} + 3 \cdot 4 \cdot x^{2} \cdot (- 3 y) + 3 \cdot 2 x \cdot 9 \cdot y^{2} - 27 \cdot y^{3}$

$= 8 x^{3} - 36 x^{2} y + 54 x y^{2} - 81 y^{2}$

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