Násobení lomených výrazů

$\huge\frac{2c^3}{3a} \times \frac{-4a}{5bc^2} = -\frac{8c}{15b}$

$a \neq 0$

$b \neq 0$

$c \neq 0$

$\huge\frac{-3x}{4z} \times \frac{15x}{9y} \times \frac {6y}{5z} = \frac{-x}{2z} \times \frac{5x}{3y} \times \frac {3y}{z} = \frac{-x}{2z} \times \frac{5x}{1} \times \frac {1}{z}= -\frac{5x^2}{2z^2}$

$y \neq 0$

$z \neq 0$

$\huge\frac{9a^2b^5}{12c^2} \times \left(-\frac{2c}{ab^2} \right)^2 = \frac{9a^2b^5}{12c^2} \times \frac{4c^2}{a^2b^4} = \frac{9b}{3} \times \frac{1}{1} = 3b$ 

$a \neq 0$

$b \neq 0$

$c \neq 0$

$\huge\left(-2x^2y \right)^2 \times \frac{x+y}{8x^3y^2}=\frac{4x^4y^2}{1} \times \frac{x+y}{8x^3y^2} = \frac{x}{1} \times \frac{x+y}{2} = \frac{x\left(x+y \right)}{2}$ 

$x \neq 0$

$y \neq 0$

$\huge\left(4x-5y \right) \times \frac{-3y}{20y-16x} = \frac{4x-5y }{1} \times \frac{-3y}{4 \left(5y-4x \right)} = \frac{4x-5y}{1} \times \frac{-3y}{-4 \left(4x-5y \right)} =\\ \huge \frac{1}{1} \times \frac{-3y}{-4} = \frac{3y}{4}$

$4x -5y\neq 0$

$4x\neq 5y$

$x\neq \frac{5y}{4}$