Tính tổng bốn đơn thức đồng dạng

Ta có: \(\begin{array}{l} S = 2x^2y^3 + \left(-\dfrac{3}{5}x^2y^3\right) + \left(-14x^2y^3\right) + \dfrac{8}{5}x^2y^3 \\[6pt] = 2x^2y^3 - \dfrac{3}{5}x^2y^3 - 14x^2y^3 + \dfrac{8}{5}x^2y^3 \\[6pt] = \left(2 - \dfrac{3}{5} - 14 + \dfrac{8}{5}\right)x^2y^3 \\[6pt] = \left(\dfrac{10}{5} - \dfrac{3}{5} - \dfrac{70}{5} + \dfrac{8}{5}\right)x^2y^3 \\[6pt] = \dfrac{10 - 3 - 70 + 8}{5} \cdot x^2y^3 \\[6pt] = \dfrac{-55}{5} \cdot x^2y^3 \\[6pt] = -11x^2y^3. \end{array}\)